Modified Bacillus thuringiensis genes with improved expression in plant cells, methods of production on and use

ABSTRACT

The invention relates to modified Bacillus thurigiensis genes with improved expression in plant cells, their preparation and uses. The invention relates more particularly to DNA fragments encoding all or part of a Bt insecticidal crystal protein, modified by translationally neutral modification(s) in cryptic promoter(s) and/or abortive intron(s). The invention also discloses method of preparing such modified DNAs, and methods of protecting plants from an insect pest.

This invention provides a modified gene, such as a Bacillus thuringiensis ("Bt") gene (the "modified Bt ICP gene") encoding all or an insecticidally-effective portion of a Bt insecticidal crystal protein ("ICP"). A plant, transformed with the modified gene, shows higher expression levels of the encoded protein.

BACKGROUND OF THE INVENTION

Plant genetic engineering technology has made significant progress during the last 10 years. It has become possible to introduce stably foreign genes into plants. This has provided exciting opportunities for modern agriculture. Derivatives of the Ti-plasmid of the plant pathogen, Agrobacterium tumefaciens, have proven to be efficient and highly versatile vehicles for the introduction of foreign genes into plants and plant cells. In addition, a variety of free DNA delivery methods, such as electroporation, microinjection, pollen-mediated gene transfer and particle gun technology, have been developed for the same purpose.

The major aim of plant transformations by genetic engineering has been crop improvement. In an initial phase, research has been focussed on the engineering into plants of useful traits such as insect-resistance. In this respect, progress in engineering insect resistance in transgenic plants has been obtained through the use of genes, encoding ICPs, from Bt strains (Vaeck et al, 1987). A Bt strain is a spore forming gram-positive bacterium that produces a parasporal crystal which is composed of crystal proteins which are specifically toxic against insect larvae. Bt ICPs possess a specific insecticidal spectrum and display no toxicity towards other animals and humans (Gasser and Fraley, 1989). Therefore, the Bt ICP genes are highly suited for plant engineering purposes.

For more than 20 years, Bt crystal spore preparations have been used as biological insecticides. The commercial use of Bt sprays has however been limited by high production costs and the instability of crystal proteins When exposed in the field (Vaeck et al, 1987). The heterogeneity of Bt strains has been well documented. Strains active against Lepidoptera (Dulmage et al, 1981), Diptera (Goldberg and Margalit, 1977) and Coleoptera (Krieg et al, 1983) have been described.

Bt strains produce endogenous crystals upon sporulation. Upon ingestion by insect larvae, the crystals are solubilzed in the alkaline environment of the insect midgut giving rise to a protoxin which is subsequently proteolytically converted into a toxic core fragment or toxin of 60-70 Kda. The toxin causes cytolysis of the epithelial midgut cells. The specificity of Bt ICPs can be determined by their interaction with high-affinity binding sites present on insects' midgut epithelia.

The identification of Bt ICPs and the cloning and sequencing of Bt ICP genes has been reviewed by Hofte and Whiteley (1989). The Bt ICP genes share a number of common properties. They generally encode insecticidal proteins of 130 kDa to 140 kDa or of about 70 kDa, which contain toxic fragments of 60±10 kDa (Hofte and Whiteley, 1989). The Bt ICP genes have been classified into four major groups according to both their structural similarities and insecticidal spectra (Hofte and Whiteley, 1989): Lepidoptera-specific (CryI), Lepidoptera- and Diptera-specific (CryII), Coleoptera-specific (CryIII) and Diptera-specific (CryIV) genes. The Lepidoptera-specific genes (CryI) all encode 130-140 kDa proteins. These proteins are generally synthesized as protoxins. The toxic domain is localized in the N-terminal half of the protoxin. Deletion analysis of several CryI genes confirm that 3' portions of the protoxins are not absolutely required for toxic activity (Schnepf et al, 1985). CryII genes encode 65 kDa proteins (Widner and Whiteley, 1985). The CryIIA proteins are toxic against both Lepidoptera and Diptera while the CryIIB proteins are toxic only to Lepidopteran insects. The Coleoptera-specific genes (CryIII) generally encode proteins with a molecular weight of about 70 kDa (Hofte and Whiteley, 1989). The CryIIIA gene expressed in E. coli directs the synthesis of a 72 kDa protein which is toxic for the Colorado potato beetle. This 72 kDa protein is processed to a 66 kDa protein by spore-associated bacterial proteases which remove the first 57 N-terminal amino acids (McPherson et al, 1988). Deletion analysis demonstrated that this type of gene cannot be truncated at its 3'-end without the loss of toxic activity (Hofte and Whiteley, 1989). Recently an anti-coleopteran strain, which produces a 130 kDa protein, has also been described (European patent application ("EPA") 89400428.2). The CryIV class of crystal protein genes is composed of a heterogeneous group of Diptera-specific crystal protein genes (Hofte and Whiteley, 1989).

The feasibility of generating insect-resistant transgenic crops by using Bt ICPs has been demonstrated (Vaeck et al, 1987; Fischhoff et al, 1987 and Barton et al, 1987). Transgenic plants offer an attractive alternative and provide an entirely new approach to insect control in agriculture which is at the same time safe, environmentally attractive and cost-effective (Meeusen and Warren, 1989). Successful insect control has been observed under field conditions (Delannay et al, 1989; Meeusen and Warren, 1989).

In all cases, Agrobacterium-mediated gene transfer has been used to express chimeric Bt ICP genes in plants (Vaeck et al, 1987; Barton et al, 1987; Fischhoff et al, 1987). Bt ICP genes were placed under the control of a strong promoter capable of directing gene expression in plant cells. It is however remarkable that expression levels in plant cells were high enough only to obtain insect-killing levels of Bt ICP genes when truncated genes were used (Vaeck et al, 1987; Barton et al, 1987). None of the transgenic plants containing a full-length Bt ICP gene produced insect-killing activity. Moreover, Barton et al. (1987) showed that tobacco calli transformed with the entire Bt ICP coding region became necrotic and died. These results indicate that the Bt ICP gene presents unusual problems that must be overcome to obtain significant levels of expression in plants. Even when using a truncated Bt ICP gene for plant transformation, the steady state levels of Bt ICP mRNA obtained in transgenic plants are very low relative to levels produced by both an adjacent NPT II-gene, used as a marker, and by other chimeric genes (Barton et al, 1987; Vaeck et al, 1987). Moreover, the Bt ICP full size mRNA cannot be detected by Northern blot analysis. Similar observations were made by Fischhoff et al. (1987); they reported that the level of Bt ICP mRNA was much lower than expected for a chimeric gene expressed from the CaMV35S promoter. In other words, the cytoplasmic accumulation of the Bt mRNA, and consequently the expression of the Bt ICP protein in plant cells, are extremely inefficient. By contrast, in microorganisms, it has been shown that truncated Bt ICP genes are less favorable than full-length genes (Adang et al, 1985), indicating that the inefficient expression is solely related to the heterologous expression of Bt ICP genes in plants.

The problem of obtaining significant Bt ICP expression levels in plant cells seems to be inherent and intrinsic to the, wild-type Bt ICP genes. Furthermore, the relatively low and poor expression levels obtained in plants appears to be a common phenomenon for all Bt ICP genes.

It is known that there are six steps at which gene expression can be controlled neucaryotes (Darnell, 1982):

1) Transcriptional control

2) RNA processing control

3) RNA transport control

4) mRNA degradation control

5) translational control

6) protein activity control

For all genes, transcriptional control is considered to be of paramount importance (The Molecular Biology of the Cell, 1989).

In European patent publications ("EP") 385,962 and 359,472 efforts to modify the codon usage of Bt ICP genes to improve their expressions in plant cells have been reported. However, wholesale (i.e., non-selective) changes in codon usage can introduce cryptic regulatory signals in a gene, thereby causing problems in one or more of the six steps mentioned above for gene expression, and thus inhibiting or interfering with transcription and/or translation of the modified foreign gene in plant cells. For example, changes in codon usage can cause differential rates of mRNA production, producing instability in the mRNA, so produced (e.g., by exposure of regions of the mRNA, unprotected by ribosomes, to attack and degradation by cytoplasmic enzymes). Changes in codon usage also can inadvertantly interfere with expression of the so-modified gene. EP 359,472 suggests that plant consensus splice sites, if present in the native Bt tenebrionis coding region, be modified so as to eliminate potentially deleterious sequences.

PCT patent publication WO 91/16432 describes the slow rate and/or level of nuclear production of a Bt ICP mRNA as an important cause of the relatively low expression levels of Bt ICP genes in plant cells. In particular, RNA polymerase elongation was found to be hindered in a specific region of the genes.

SUMMARY OF THE INVENTION

In accordance with this invention is provided a process for modifying a gene, preferably a Bt ICP gene, particularly a cryI gene, quite particularly a cryIAb gene, whose level and/or rate of expression in a plant cell, transformed with the gene, is limited by the rate and/or level of nuclear production of a full length (i.e. unspliced) mRNA encoded by the gene; the process comprises the following step:

inactivating, preferably destroying or removing, in the coding region of the gene, at least one of the following process-directing sequence elements:

i) a cryptic promoter, such as a minimal promoter, in either a sense or anti-sense orientation, which can direct site-specific transcription initiation in the plant cell by partial or complete assembly of an RNA polymerase II initiation complex; particularly a cryptic promoter containing at least one DNA regulatory element such as a CCAAT sequence or a TATA sequence, or,

ii) a DNA encoding an abortive intron that, at the RNA level, causes entry of a precursor mRNA species in a splicing pathway, the precursor mRNA species being processed in such a way that the resulting mRNA species does not accumulate substantially in the cytoplasm of the plant cell;

the process-directing sequence elements preferably being inactivated by introducing translationally neutral modifications in the coding region of the gene by:

a) introducing DNA encoding an intron, known to be efficiently spliced in the plant cell, and/or

b) changing amino acid codons with others encoding the same amino acids.

Also in accordance with this invention is provided a gene to be used to transform a plant cell, preferably a Bt ICP gene, particularly a cryI gene, quite particularly a cryIAb gene, that is modified by the process of this invention (a "modified gene").

Further in accordance with this invention, a process is provided for improving the properties, e.g. insect resistance, of a plant by transforming the plant cell genome with at least one modified gene.

This invention also relates to a chimeric gene which can be used to transform plant cells and which contains the following operably-linked DNA fragments in the same transcriptional unit:

1) the coding region of the modified gene;

2) a promoter suitable for directing transcription of the modified gene in the plant cells; and

3) suitable transcript 3' end formation and polyadenylation signals for expressing the modified gene in the plant cells.

This invention further relates to:

a cell of a plant, the nuclear genome of which has been transformed to contain, preferably stably integrated therein, the modified gene particularly the chimeric gene;

cell cultures consisting of the plant cell;

a plant which is regenerated from the transformed plant cell or is produced from the so-regenerated plant, the genome of which contains the modified gene, particularly the chimeric gene, and which shows improved properties, e.g., resistance to insect pests;

seeds of the plant; and

a vector for stably transforming the nuclear genome of plant cells with the modified gene, particularly the chimeric gene.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a comparison of the transcriptional activity of neo and bt884 genes in nuclei of N28-220 of Example 1;

FIG. 2 is a schematic representation of the DMS footprint of the bt884 coding region between nucleotides 668 and 834.

FIG. 3A is a schematic view of the bt884 coding region with four PCR primer sets of Example 4.

FIG. 3B is schematic views of three DNA fragments (I, II and III) obtained by PCR reactions with primers PS58 and PS59.

DETAILED DESCRIPTION OF THE INVENTION

"Gene" as used herein means a DNA sequence encoding a protein, preferably a Bt ICP. This includes a modified or synthetic DNA sequence, as well as a naturally occurring DNA sequence, encoding a protein.

"Coding region" as used herein means that part of a gene that specifies the amino acid sequence of a protein. In general, a coding region comprises a plurality of translational codons that correspond to the translated part of the fully processed mRNA.

"Bt ICP gene" as used herein means a DNA sequence encoding a Bt ICP which is derived directly or indirectly from B. thuringiensis. This includes a modified, a synthetic or a naturally occurring DNA sequence, encoding a Bt ICP.

As used herein, "truncated Bt gene" should be understood as a fragment of a full-length Bt gene which still encodes at least the toxic part of the Bt ICP, preferentially the toxin.

As used herein, "Bt ICP" should be understood as an intact protein which can be produced in nature by B. thuringiensis or a part or derivative of such a protein which has insecticidal activity. A Bt ICP can be a protoxin, as well as an active toxin or other insecticidal truncated part of a protoxin which need not be crystalline and which need not be a naturally occurring protein. An example of a Bt ICP is a Bt2 insecticidal crystal protein (Hofte et al, 1986; the terminology of Bt2 is according to Hofte and Whiteley (1989) "CryIAb"), as well as its insecticidally effective parts which are truncated at its C- and/or N-terminal ends towards its trypsin cleavage site(s) and preferably having a molecular weight of 60-80 kDa. Other examples of Bt ICPs are: lepidopteran-active ICPs like Bt3, Bt4, Bt14, Bt15, Bt18, Bt73, cryIG described in Gleave et al 1992), cryIF described in EP 405,810; and coleopteran-active ICPs like: Bt13, Bt21, Bt22, BtI260 and BtI109P as disclosed in PCT publications WO 90/15139 and WO 90/09445, in Hofte and Whiteley (1989) and in EPA 90403724.9, or any modified or hybrid ICPs having insecticidal activity.

As used herein, "protoxin" should be understood as the primary translation product of a full-length gene encoding a Bt ICP.

As used herein, "toxin" or "active toxin" or "toxic core" should all be understood as a part of a protoxin which has insecticidal activity and which can for instance be obtained by protease (e.g. by trypsin) cleavage.

As used herein, a "process-directing sequence element" is a genetically cis-acting regulatory element that is either a DNA encoding an abortive intron or is a cryptic promoter whose presence in the coding region of a gene in a plant cell substantially inhibits or prevents the gene's transcription to a full length mRNA, the nuclear accumulation of a full length mRNA and/or the nuclear export of a full length mRNA. Such a sequence element can be different from known plant promoters or plant introns in a given plant cell. A process-directing sequence element would, if not inactivated, actually be recognized by a plant cell and thereby would interfere with gene expression in the plant cell. A genetically cis-acting regulatory element of this invention is believed to be involved in, and/or responsible for, a gene expression-controlling step, such as is listed in the Background of the Invention, that interferes with gene, particularly Bt ICP gene, expression in plant cells.

A "cryptic promoter", such as a "minimal promoter", as used herein means a DNA sequence which is located within the coding region of a protein-encoding gene in either a sense or anti-sense orientation and which can direct site-specific transcription initiation in a given plant cell by partial or complete assembly of an RNA polymerase II initiation complex. Such cryptic promoters are believed to be active due to the presence of so-called "DNA regulatory elements" which are cis-acting, such as the CCAAT and TATA sequences, which specifically interact with nuclear factors. It appears that a cryptic promoter interferes with gene expression by interacting with nuclear proteins and thereby causing transcriptional interference to RNA polymerase II transcribing the gene, or by being transcriptionally active and thereby specifying, depending on its orientation within the gene, a sense or anti-sense RNA, causing sense or anti-sense suppression of gene expression.

A "DNA regulatory element" herein is a sequence in a promoter region that is involved in the partial or complete assembly of an RNA polymerase II initiation complex. Known examples of such DNA regulatory elements are the TATA box and the CCAAT box (Ha and An, 1989; Paul et al, 1987), which in many plant promoters are separated by about 20 to 50 nucleotides, with the TATA box being located about 32±7 nucleotides upstream from the transcription initiation site (Joshi, 1987). Other known DNA regulatory elements are, for example, those listed by Katagiri and Chua (1992).

A "precursor mRNA" or "pre-mRNA" refers to the protein-encoding RNA that is transcribed from the DNA in the nucleus of a plant cell. A pre-mRNA can be further processed, for instance by the removal of plant introns, and the fully-processed or mature mRNA is ultimately translated in the cytoplasm of the plant cell. As used herein a "full length mRNA", a "fully processed mRNA", or a "mature mRNA" is an mRNA that can be translated in the cytoplasm and encodes the protein encoded by the gene.

"Abortive splicing" as used herein is a process in which a precursor mRNA species enters a splicing pathway of a plant cell and is processed in such a way that the spliced mRNA does not accumulate substantially in the plant cell cytoplasm, e.g. the mRNA decays during or after splicing in the nucleus before transport to the cytoplasm or it decays rapidly in the cytoplasm. It appears that in abortive splicing, only a relatively small number of the pre-mRNAs are effectively processed with removal of an intron and subsequent junction of the exon, whereby only the actually spliced mRNAs are detectable in some or all plant cells. Abortive splicing should not be confused with partially active splicing in which a majority of the pre-mRNAs which enter the splicing pathway are effectively spliced, but with only a low frequency of such pre-mRNAs actually entering the splicing pathway.

An "abortive intron" is any RNA sequence which is present in a pre-mRNA and which is removed when the pre-mRNA is abortively spliced in a plant cell. A gene may encode more than one abortive intron, and it is believed that abortive splicing thereof is part of an ordered process with dominant intron(s) being spliced out first and with less dominant introns being spliced out later in a plant cell.

"Abortive intron splice sites" as used herein are those nicking sites at the 5' and 3' sides of an abortive intron at which splicing occurs in any pre-mRNA that is abortively spliced.

In accordance with this invention, a cryptic promoter in the coding region of a particular gene, preferably a Bt ICP gene, can be detected by the following procedure:

In a first step a region (the "pausing region") is identified in the gene where transcription elongation is substantially inhibited. Pausing is the process by which the elongation rate of RNA polymerase II, active in transcription, reduces. Pausing differs from termination in that RNA polymerase II remains associated to the template and can resume RNA synthesis. A pausing region in a transcription unit can be determined by measuring the transcriptional activity of RNA polymerase II complexes transcribing the gene, for example by run-on analysis as described in PCT patent publication WO 91/16432, for consecutive, partially overlapping regions of the gene of about 300 nucleotides, preferably of about 200 nucleotides, particularly of about 100 nucleotides. A pausing region corresponds to such region in which the transcriptional activity is low, preferably less than 20%, particularly less than 10%, quite particularly less than 5% relative to the activity in a region of about 300 nucleotides directly downstream of the transcription initiation site, particularly when the run-on assay is performed for a prolonged time period, i.e. for a period of 5 to 10 minutes. Nuclei to be used in the run-on assay can be obtained by nuclei purification methods using either transiently or stably transformed cells carrying the gene respectively extra- or intra-chromosomally. If transgenic plants are available in which the nuclear genome is transformed with the gene under control of appropriate plant gene regulatory sequences, the pausing region can be determined by nuclear run-on assays, supplemented by DMS footprinting analysis, as for instance described in the examples, and/or the KMNO pausing assay (Morrett and Buck, 1989; Sasse-Dwight and Gralla, 1988; Cannon et al, 1990).

Once the pausing region has been determined parts or all of it (generally regions of about 100 to 300 nt in length) can be cloned into two orientations in a suitable transcription initiation-probe vector (Cornelissen and Vandewiele, 1989a). Such a vector can, for example, be obtained by placing part or all of the pausing region downstream of an enhancer of a plant promoter and upstream of a DNA sequence that can be transcribed and the transcript of which can be uniquely detected in plant cells. A preferred example of such an enhancer is the enhancer or "B" region of the 35S promoter as described by Benfey et al (1990), but other known enhancer regions can also be used (as for instance the enhancer of the TR2' promoter). Preferred examples of a transcribable region in the transcription initiation probe-vector are the coding regions of the bacterial chloramphenicol acetyl transferase gene (cat) or the basta-resistance gene (Cornelissen and Vandewiele, 1989a), followed by a suitable 3' end formation and polyadenylation sequence. When these vectors are introduced into plant cells such as tobacco or maize protoplasts, one can then detect the accumulation of particular transcript species which are initiated from the presumed cryptic promoter by hybridization with a probe derived from the transcribable region of the transcription initiation probe-vector. Primer extension analysis or Si mapping of the transcripts then allows the determination of the transcription initiation site which in turn facilitates the detection of potential DNA regulatory elements, such as CCAAT and TATA boxes that are recognized by the plant cell. If known DNA regulatory elements in a suitable configuration to be recognized by the plant cell (e.g. a CCAAT box and a TATA box separated by about 20 to 50 nucleotides) are found in the sequence this is already a strong indication of the presence of a cryptic promoter and this can be confirmed by assaying for the ability to initiate transcription by placing the region containing these elements in the transcription initiation-probe vector as described above. Typically the start site of transcription is maintained when the enhancer is moved relative to the cryptic promoter over distances shorter than 50 nucleotides, preferably 100 nucleotides, more preferably 200 nucleotides.

In accordance with this invention, an abortive intron in the coding region of a particular gene, preferably a Bt ICP gene, can be detected by the following procedure:

The coding region of the gene is placed under control of suitable plant regulatory sequences in a suitable vector and introduced in plant cells, such as tobacco or maize protoplasts. About 5 to 7 hours after DNA delivery, total RNA is extracted. cDNA is prepared from the mRNA that is present in the plant cells according to conventional methods. Subsequently overlapping regions of the full size precursor mRNA expected to be produced from the introduced gene are amplified by means of PCR, using the previously synthesized cDNA as a substrate and using gene specific oligonucleotide primer pairs that lie between the transcript start site and the 3' end formation site.

In general overlapping regions of about 500 to 700 nucleotides are amplified, but this can be supplemented with amplification of increasingly larger overlapping regions e.g. amplification of overlapping regions of about 1000 nucleotides possibly followed by amplification of overlapping regions of about 2000 nucleotides will be generally suitable for this purpose.

The amplified products are then analyzed and any product that is smaller in size than that expected on the basis of full-size, mature mRNA is purified and sequenced. A comparison of the sequence of such shorter amplified products with the sequence of the expected full size precursor mRNA then allows the identification of gaps in the amplified products corresponding to introns. This in turn allows the identification of presumed intron splice sites at the 5' and 3' ends of the introns in the expected full-size mRNA. Inactivation of the 5' splice site and reintroduction of the gene into plant cells will allow to distinguish between abortive and partially active introns. If the intron is abortive, inactivation of the splice site will result in significant increases in full size mRNA levels, whereas inactivation of the partially active intron will result in a marginal increase of the full length mRNA level.

The routine system used for the identification of cryptic promoters or abortive introns as described above is the transient expression (TEX) protoplast system. For dicots, tobacco cells are preferred for the identification of the active process-directing sequence elements; for monocots, corn or rice cells provide the preferred test system. Of course, any plant cell, known in the art as suited for transient or stable transformation, can be used.

The identification and characterization of cryptic promoters and/or abortive introns of this invention allows the recognition of relatively small DNA sequence elements (the "target sequences") and their modification so as destroy the activity of these process- directing sequence elements in the plant cell.

It is preferred that such modifications be translationally neutral. "Translationally neutral modifications" as used herein are modifications that do not affect the amino acid sequence of the protein encoded by the gene. Preferred examples of such translationally neutral modifications are the changing, by means of nucleotide substitutions in the gene, of amino acid codons into others codons that encode the same amino acids. Such nucleotide substitutions can change A and T nucleotides into C and G nucleotides (PCT patent publication WO 91/16432), and for certain other translationally neutral modifications, C and G nucleotides may be changed to A and T nucleotides. Another preferred example of translationally neutral modifications is the introduction in the gene of at least one intron, known to be efficiently spliced in plant cells, so that the gene is transcribed into a precursor mRNA that is efficiently processed, by means of splicing of the introduced intron, into a mature mRNA that codes for the protein, preferably the Bt ICP. An intron known to be efficiently spliced in plant cells is any intron that is efficiently spliced out of a precursor mRNA in the plant cell. A suitable intron for use in plants, preferably in dicots, is the TA36 intron, as described in PCT patent publication WO 92/13957 or any other functional plant intron. Appropriate sites for insertion of the TA 36 intron or any other functional plant intron are determined according to well known general rules as outlined, for example, in Goodall and Filipowicz (1989) and Hanley and Schuler (1988).

Of course, translationally neutral nucleotide substitutions can be combined with the introduction of such introns in a foreign gene to be expressed in a plant.

The DNA regulatory elements, such as the CCAAT and/or TATA boxes, present in a cryptic promoter are preferred target sequences for modification. Thus the sequence of such DNA regulatory elements can be changed by transitionally neutral nucleotide substitutions of selected nucleotides and/or by insertion in that sequence of a suitable plant intron. However, plant cell recognition of the cryptic promoter can be reduced or eliminated by making substantial translationally neutral changes throughout the zone of 20 to 90, preferably 20 to 50, nucleotides upstream of the experimentally determined transcription initiation site. Preferably, such substantial changes will comprise making the maximum possible number of translationally neutral nucleotide substitutions within this zone. Also, the introduction of a suitable plant intron at any appropriate position in this zone is believed to reduce the activity of the cryptic promoter.

With respect to the abortive introns, it is believed that the abortive intron splice sites are of particular importance or the entry of the precursor mRNA containing the abortive intron in the abortive splicing pathway. Abortive introns are preferably inactivated by translationally neutral modifications in the coding region of the gene, preferably the Bt ICP gene, in the sequence corresponding to that surrounding at least the 5' (or upstream) abortive splice site in the precursor mRNA transcribed from the gene in a plant cell. Of course these modifications may be supplemented with, or even replaced by, modifications in the sequence of the coding region corresponding to that surrounding the 3' (or downstream) abortive splice site and/or the branch point (Brown, 1986). Preferred target sequences are thus believed to be a sequence of about 10 nucleotides, particularly a sequence of about 5 nucleotides, quite particularly a sequence of about 3 nucleotides, on either side of the sites that, in the precursor mRNA transcribed from the gene, correspond to the 5' and/or 3' abortive splice sites of the abortive intron, preferably its 5' GT and/or its 3' AG nucleotides. Abortive introns according to this invention have certain essential characteristics of plant introns as described for example by Goodall and Filipowicz (1989, 1990). Furthermore, examples of target sequences for abortive intron modification can be found in the consensus RNA sequences essential for intron splicing (Padgett et al, 1986; Aebi and Weismann, 1988) in plant cells as described by Hanley and Schuler (1988) as follows (' refers to the splice position): N A/U G' G U A A G U/A A/U U/A U/A at the 5' border of introns of dicots and U/A U/A U/N U/A U/A U/A U/A A/U U/A U/A U G/A C/U A G' at the 3' border of introns of dicots; and A/C/G A G' G U A A/U C U/C U/A U/C U/N at the 5' border of introns of monocots and U/C U/C U/G U/A U/C U/G U/N U/N U G/N C A G' at the 3' border of introns of monocots. Surprisingly, many non-plant genes, particularly Bt ICP genes, have been found to encode the following portions of the consensus RNA sequences of Hanley and Schuler (1988) that are essential for intron splicing in plant cells: GUAAG or GUAUG, particularly GUAAG, downstream (i.e., 3') of the upstream (i.e., 5') intron splice position; and AG upstream of the downstream intron splice position.

Thus the modification of a cryptic promoter and/or of the DNA encoding an abortive intron, preferably in specific target sequences, particularly by removing the essential characteristics or destroying the DNA encoding the consensus RNA sequences, as described above, results in an increased amount of full-size mRNA that can be translated to produce the protein encoded by the gene.

As used herein, "modified gene" should be understood as a DNA sequence, preferably one that encodes a Bt ICP, and in which, in at least one process-directing sequence element of the coding region, the nucleotide content of at least one codon has been changed by a translationally neutral modification that results in the inactivation of such a process-directing sequence element. Preferably, only minor modifications are made go the coding region of the Bt ICP gene. In particular, the modifications involve changing less than 10%, preferably less than 3%, particularly less than 1%, of the nucleotides in the coding region. In this regard, less than 10%, preferably less than 3%, particularly less than 1%, of the nucleotides in the coding region of the gene are changed from A or T nucleotides to G or C nucleotides. However, modifications of the coding region in accordance with this invention do not require the introduction of plant preferred codons, nor do they require that only A and T nucleotides are changed to G and C nucleotides. Preferably, each of the process-directing sequence elements is modified by changing only few nucleotides, so that the element is inactivated in the given plant cell, and so that the nucleotides encode the same amino acids. However, in some instances, some amino acids can be changed, such as when an encoded Bt ICP retains at least substantially the same insecticidal properties.

This invention is preferentially applied to genes which are to be expressed into certain plant species but that originate from organisms that are only distantly related to those plant species, e.g., expressing bacterial or animal genes in plants, monocot genes in dicots or dicot genes in monocots. In this regard the invention is particularly useful for modifying genes which are A+T-rich, particularly genes which contain more than 50% A+T in certain regions, such as Bt ICP genes, especially the cryI genes, more specifically the cryIAb gene.

The present invention will be exemplified by means of the cryIAb or bt2 gene of Bacillus thuringiensis. Thus it has been shown previously that the expression pathway of a Bt ICP gene, such as bt2, bt14, bt15 and bt18, is specifically inhibited at the nuclear level in plant cells (PCT patent publication WO 91/16432 which is incorporated herein as reference). Nuclear run-on analysis with N28-220 nuclei, originating from tobacco cells and containing the bt884 construct (Vaeck et al., 1987), indicated that transcription elongation of the nascent Bt ICP mRNA was impaired between or close to nucleotides 700 to 1000 downstream of the start of transcription. Filter binding assays using labeled Bt DNA fragments spanning this region and protein extract prepared from tobacco nuclei revealed that this DNA region undergoes specific interactions with proteins present in nuclei (PCT publication WO 91/16432).

In vivo transcription initiation assays (Cornelissen and Vandewiele, 1989a) in which the 474 bp EcoRV-Bst1107I bt884 fragment is positioned downstream of the CAMV 35S enhancer, have now revealed that this region functions as a minimal promoter in tobacco and as such can interact with nuclear transcription factors. These interactions are the prime candidates that cause or affect the impaired elongation of transcription by RNA polymerase II through this region. By modification of this region to abolish specific protein binding, Bt ICP expression levels will increase. This region has been found to contain CCAAT- and TATA-sequences, which are conserved motifs, found in promoters of diverse origin (The Molecular Biology of the Cell, 1989).

Deletion analysis suggested that the low transcript levels produced by Bt ICP genes were not controlled by a single factor (PCT publication WO 91/16432). A study of the polyadenylated bt884 transcripts in N28-220 by cDNA-PCR revealed the occurrence of minor quantities of shorter transcript species. Sequence analysis of the PCR products demonstrated the presence of three cryptic introns in the bt884 coding region. It can not be excluded that additional or other splicing events, including abortive splicing, take place when the bt884 is expressed in other plant species. In accordance with the deletion analysis, this finding demonstrates that a plurality of inhibitory zones are present in the bt884 coding region.

Nevertheless, individual modifications of the bt884 or cryIAb6 coding region can significantly reduce the interference and/or inhibition of the expression of the full length mRNA encoded by the genes in plant cells at the level of transcript elongation, nuclear processing, nuclear accumulation and nuclear export. The modification(s) may also affect cytoplasmic regulation and metabolism of such mRNAs and their translation.

In addition, substitution mutations were made at the 5' splice sites of each of the three cryptic introns. These mutations are translationally neutral, and as such abolish splicing of the respective introns. bt884 or cryIAb6 genes carrying these modifications direct significantly higher levels of full length mRNA and ICP in tobacco cells compared to the wild-type gene.

Instead of modifying the codon usage of one or more inhibitory zones in a Bt ICP gene, such as bt884 or cryIAb6, at least one process-directing sequence element in each such zone, preferably each of such sequence elements in each inhibitory zone, is inactivated, preferably split by providing at least one intron within it. The intron preferably provided in the inhibitory sequence is efficiently spliced in the plant cell, and is not intended to provide a so-called "intron-mediated elevation of gene expression" as has been reported for several genes that were transiently introduced in corn cells (Callis et al, 1987). Instead, the intron is intended to destroy the functioning of the inhibitory sequences by dividing the sequence in two. This modification leaves the coding region of the Bt ICP gene otherwise unaffected, while changing its regulatory features in regard to processes preceding the accumulation of mature mRNA in the nucleus and/or cytoplasm. However, to optimize the splicing efficiency of precursor mRNAs, it may be necessary to modify the nucleotides flanking the introduced intron, preferably with at most three nucleotides, spread over at most two translational codons, to create optimal 5' and 3' splice boundaries. According to Brown (1986), 38 out of 64 possible nucleotide triplets can each serve as a 5' exon boundary flanking an intron in an endogenous plant gene in a plant, and any nucleotide can be used at the 3' exon boundary flanking such an intron. Triplets not described by Brown (1986) can also function as such 5' exon boundaries in a plant.

By way of example the 5' splice site of intron 2 was interrupted in the cryIAb6 coding region by introducing the intron sequence of the tobacco gene TA36. This modified gene directs elevated levels of full length cryIAb6 mRNA in tobacco cells.

In the modified Bt ICP gene all process-directing sequence elements, active in the plant cell, can be removed or destroyed, or only some can be removed or destroyed, depending on the expression level desired.

Preferably, the modified gene, such as the modified Bt ICP gene, is inserted in a plant genome downstream of, and under the control of, a promoter which can direct the expression of the gene in the plant cells. Preferred promoters include, but are not limited to, the strong constitutive 35S promoter (Odell et al, 1985) or duplicated 35S promoter (Kay et al, 1987) of cauliflower mosaic virus; 35S promoters have been obtained from different isolates (Hull and Howell, 1987). Other preferred promoters include the TP1' promoter and the TR2' promoter (Velten et al, 1984). Alternatively, a promoter can be utilized which is not constitutive but rather is specific for one or more tissues or organs. For example, the modified gene can be selectively expressed in the green tissues of a plant by placing the gene under the control of a light-inducible promoter such as the promoter of the ribulose--1,5--biphosphate--carboxylase small subunit gene as described in EPA 86300291.1. Another alternative is to use a promoter whose expression is inducible by temperature or chemical factors.

It is preferred that the coding region of the modified gene, such as the modified Bt ICP gene, be inserted upstream of suitable 3' transcription regulation signals (i.e., transcript 3' end formation and polyadenylation signals) derived from the chalcone synthase gene (Sommer and Saedler, 1986) or Cauliflower Mosaic Virus (Mogen et al, 1990), the octopine synthase gene (Gielen et al, 1984), or T-DNA gene 7 (Velten and Schell, 1985).

In accordance with this invention, all or part of a modified gene of this invention, such as a modified Bt ICP gene, can be stably inserted in a conventional manner into the nuclear genome of a plant cell, and the so-transformed plant cell can be used to produce a transgenic plant showing improved expression of the modified gene. In this regard, a disarmed Ti-plasmid, containing the modified gene, in Agrobacterium (e.g., A. tumefaciens) can be used to transform a plant cell using the procedures described, for example, in EP 116,718 and EP 270,822, PCT publication 84/02913, EPA 87400544.0 and Gould et al (1991) (which are incorporated herein by reference). Preferred Ti-plasmid vectors contain the foreign DNA sequence between the border sequence, or at least located to the left of the right border sequence, of the T-DNA of the Ti-plasmid. Of course, other types of vectors can be used to transform the plant cell, using procedures such as direct gene transfer (as described, for example, in EP 233,247), pollen mediated transformation (as described, for example, in EP 270,356 PCT publication WO85/01856, and U.S. Pat. No. 4,684,611), plant RNA virus-mediated transformation (as described, for example, in EP 67,553 and U.S. Pat. No. 4,407,956), liposome-mediated transformation. (as described, for example, in U.S. Pat. No. 4,536,475) and other methods such as the methods for transforming monocots such as the major cereals including corn, rice, wheat, barley and rye, as described in PCT patent publication WO 92/09696. In case the plant to be transformed is corn, other recently developed methods can also be used such as, for example, the method described for certain lines of corn by Fromm et al (1990), Gordon-Kamm et al (1990), and Gould et al (1991). In case the plant to be transformed is rice, recently developed methods can also be used such as, for example, the method described for certain lines of rice by Shimamoto et al (1989), Datta et al (1990) and Hayashimoto et al (1990).

The resulting transformed plant of this invention shows improved expression of the modified gene, such as the modified Bt ICP gene, and hence is characterized by the production of high levels of protein, such as Bt ICP, encoded by the gene. Such a plant can be used in a conventional breeding scheme to produce more transformed plants with the same improved properties such as insect-resistance characteristics or to introduce the modified gene like the modified Bt ICP gene into other varieties of the same or related plant species. Seeds, which are obtained from the transformed plants, contain the modified gene as a stable genomic insert. It is believed that expression of a foreign gene in a plant can be improved in accordance with this invention for any plant such as corn, soybean, oilseed rape, wheat, lettuce, tomato and potato. However, the modification of genes intended to be expressed in monocots may require the translationally neutral modification of process-directing sequence elements having different DNA or RNA sequences from those active in dicots.

Furthermore, at least two modified Bt ICP genes, coding for two non-competitively binding Bt ICPs, can be cloned into a plant expression vector (EPA 89401499.2). Plants transformed with such a vector are characterized by the simultaneous expression of at least two modified Bt ICP genes. The resulting transgenic plant is particularly useful to prevent or delay development of resistance to Bg ICP of insects feeding on the plant.

This invention is thus based on the discovery that the coding region of foreign genes, particularly bacterial genes, quite particularly Bt ICP genes, may contain genetically cis-acting regulatory elements in their coding regions, particularly cryptic promoters and abortive introns, that seriously hamper the expression of these genes when they are introduced, under control of appropriate plant regulatory sequences such as plant promoters and 3' untranslated ends, in a plant cell environment. The discovery of such sequences allows the directed and limited modification of target sequences within the coding regions of such genes. In general less than about 10%, preferably less than about 3%, nucleotide modifications in the coding region are required in order to substantially alleviate the expression problem. Because only a relatively small number of modifications result in a substantial increase of foreign gene expression in plants, the modified genes produced on accordance with this invention are unlikely to contain newly introduced sequences that interfere themselves with expression of the gene in a plant cell environment.

The following Examples illustrate the invention and are not intended to limit its scope. The Figures and Sequence Listings, referred to in the Examples, are as follows:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1--Comparison of the transcriptional activity of neo and bt884 genes in nuclei of N28-220 of Example 1. The RNA extension reaction was performed in the presence of ¹³ P UTP for 20 minutes at 30° C. Radioactively labeled RNA extracted from nuclei was hybridized with a molar excess of denatured neo and bt884 DNA which was immobilized on a nylon membrane. The positions and sizes of the DNA regions on the T-DNA are indicated. LB and RB refer to the left and right T-DNA borders, respectively. The 3' end formation and polyadenylation region of the g7 and ocs genes (Vaeck et al, 1987) are indicated. The relative abundance of hybridizing neo (left-hand column) and bt884 (right-hand column) mRNAs was measured both by scintillation counting and densitometric scanning of autoradiographs with different exposure times. Values were corrected for the UTP contents of the hybridizing RNA.

FIG. 2--Schematic representation of the DMs footprint of the bt884 coding region between nucleotides 668 and 834. Nucleotides hyper- and hypo-methylated in vivo relative to naked DNA by DMS are indicated by arrows pointing respectively downwards and upwards. See the scales at the right of the figure for quantification. All maintenance greater than 15% and hypersensitivities greater than 1.25 fold are shown. Boxed G-residues were not taken into account as the corresponding bands comigrated with dimers of the radioactively labeled primers. The CCAAT boxes are underlined.

FIG. 3A--Schematic view of the bt884 coding region with four PCR primer sets of Example 4. Nucleotide numbering is relative to the translation start codon. The orientations of the PCR primers are indicated by arrows, and the position of the 5' nucleotide of each primer is shown.

FIG. 3B--Schematic views of three DNA fragments (I, II and III) obtained by PCR reactions with primers PS58 and PS59. Numbering is relative to the translation start codon and refers to the 5' and 3' nucleotides of the introns in the bt884 coding region. The adjacent nucleotides located upstream and downstream of the 3' and 5' splice sites are shown.

Sequence Listing:

SEQ ID NO. 1: oligonucleotide PS48

SEQ ID NO. 2: oligonucleotide PS43

SEQ ID NO. 3: oligonucleotide PS38

SEQ ID NO. 4: oligonucleotide PS39

SEQ ID NO. 5: oligonucleotide PS47

SEQ ID NO. 6: oligonucleotide PS44

SEQ ID NO. 7: oligonucleotide PS38

SEQ ID NO. 8: oligonucleotide PS46

SEQ ID NO. 9: oligonucleotide PS45

SEQ ID NO. 10: oligonucleotide PS58

SEQ ID NO. 11: oligonucleotide PS59

SEQ ID NO. 12: oligonucleotide PS61

SEQ ID NO. 13: oligonucleotide PS62

SEQ ID NO. 14: oligonucleotide PS63

SEQ ID NO. 15: oligonucleotide PS64

SEQ ID NO. 16: oligonucleotide PS65

SEQ ID NO. 17: oligonucleotide PS66

SEQ ID NO. 18: oligonucleotide RVA-5a

SEQ ID NO. 19: oligonucleotide RVA-5b

SEQ ID NO. 20: oligonucleotide RVA-6a

SEQ ID NO. 21: oligonucleotide RVA-6b

SEQ ID NO. 22: plasmid pJD884

SEQ ID NO. 23: plasmid pPS0212

Unless otherwise stated in the Examples, all procedures for making and manipulating recombinant DNA are carried out by the standardized procedures described in Sambrook et al, Molecular Cloning--A laboratory Manual, Cold Spring Harbor Laboratory Press, N.Y. (1989).

Particular nucleotides in the bt884 and cryIAb6 genes, as used in the examples, are identified with respect to the sequence of the genes as given in SEQ ID NO. 22 and SEQ ID NO. 23 respectively.

Plasmid pJD884, the complete sequence of which is given in SEQ ID NO. 22, contains the bt884 gene and was used to construct plasmids pRVA0214 and pPS0212. In this regard pRVA0214 is identical to pJD884 except that the sequence containing the ATG translation initiation codon between nucleotide positions 7630 and 105 is replaced with the corresponding sequence between positions 7546 and 6 of SEQ ID NO. 23; this results in a deletion of 28 amino acids at the N-terminus of the bt884 gene, and the introduction of a Joshi translation initiation consensus sequence (The corresponding bt2-derived gene in pRVA0214 is designated as cryIAb22). Plasmid pPS0212, the complete sequence of which is given in SEQ ID NO. 23, differs from pRVA0214 by several translational neutral nucleotide substitutions in the regions located between nucleotides 1 to 30 and between 594 to 906.

EXAMPLE 1 Cryptic Promoter Activity

Nuclear run-on data obtained with transgenic tobacco N28-220, described in PCT patent publication WO 91/16432, indicated that the low nucleo-cytoplasmic full length bt884 mRNA flow is not due to interference of the bt coding region with transcription initiation at the TR2' promoter (FIG. 1) and that elongation by RNA polymerase II was inhibited between or close to nucleotides 700 and 1000 downstream of the transcriptional start site of the bt884 gene. Furthermore, DNA footprint analysis showed that in vivo DNA binding proteins interact with the bt884 DNA region between nucleotides 670 and 1202 (nucleotide positions are measured relatively to the translation initiation codon). The result of this interaction could be that RNA polymerase II complexes encounter difficulties in elongating transcripts in this region. Inspection of the region revealed the presence of a number of CCAAT boxes.

An in vitro dimethyl sulfate (DMS) footprint was carried out of the region 667 to 835, downstream of the translation start of bt884, to identify if in vivo the CCAAT boxes undergo a DNA-protein interaction. Protoplasts of N28-220 were treated for 3 minutes with 0.5% DMS, and total DNA was prepared (Dellaporta et al, 1983). A parallel reaction was carried out at pH 7.9 with 34 μg of deproteinized DNA of N28-220 in 200 μl TE (10 mM Tris, pH 7.9, 1 mM EDTA) to which 1 μl DMS was added. The incubation was stopped after three minutes by the addition of 100 μl 3M Tris, pH 8.0, followed by a phenol-chloroform extraction. The DNA samples were nicked 5' to the methylated G residues by a piperidine incubation (Maxam and Gilbert, 1980). DNA strands nicked near the bt2 (cryIAb) pausing region were amplified according to the ligation-mediated PCR method described by Mueller and Wold (1989) using 3.5 μg DNA samples for both reactions. The oligonucleotides used in the first priming reaction were: the oligonucleotide of SEQ ID NO. 1 for the coding strand and oligonucleotide of SEQ ID NO. 2 for the non-coding strand. The following linkers were ligated: the oligonucleotide of SEQ ID NO. 3 and the oligonucleotide of SEQ ID NO. 4. The ligation product was amplified by 19 PCR cycles, using for the coding and non-coding strands the respective oligonucleotides: the oligonucleotide of SEQ ID NO. 5 and the oligonucleotide of SEQ ID NO. 6, together with the lunker of SEQ ID NO. 7. A last amplification reaction of the coding and non-coding strands was done with respectively: the oligonucleotide of SEQ ID NO. 8 and the oligonucleotide of SEQ ID NO. 9 which were end-labeled with ⁻ P. The reaction products were separated on a sequencing gel and visualized by autoradiography. The lanes were scanned three times with a LKB Ultrascan 2002 (Pharmacia LKB Biotechnology, Uppsala, Sweden) and compared by alignment of the recorded profiles. The nucleotide positions were plotted versus the ratio of the densitometric values of the G-residues at the different positions fin the in vivo and in vitro DMS footprints. A linear regression was determined by reiterated calculation using points that deviated less than 20% from the average slope. Hyper- and hypo-methylation levels were determined by calculating the relative deviation of the in vivo signals for the calculated relation. The result of the DMS footprint is shown in FIG. 2. The two closely spaced CCAAT boxes, and not a separately located C box more upstream, clearly show a modulated sensitivity to DMS in vivo relative to in vitro. This strongly suggests that these boxes undergo in vivo a protein-DNA interaction. As the bt coding region has a high AT content, the CCAAT boxes might be in the proximity of a functional TATA box and thus be part of a minimal promoter. To test this hypothesis, the 474 nucleotide EcoRV-Bst1107I bt884 fragment was positioned in a sense orientation between the CaMV 35S enhancer fragment and a promoterless cat gene to monitor possible transcription initiation events (Cornelissen and Vandewiele, 1989a). When introduced into tobacco protoplasts, the 35S enhancer CCAAT box fusion directs the synthesis of two discrete cat mRNA species. An S1-protection assay was carried out essentially as described by Sambrook et al (1989) to determine the 5' nucleotides of the cat mRNAs. This resulted in the identification of three different 5' termini. The 5' termini are present in approximately equimolar ratios and map at nucleotides 774, 775, 777; nucleotides 833, 834, 836; and nucleotide 841, relative to the translation start site of bt884. This finding shows that this region functions as a minimal promoter element and as such can interact with transcription factors. The consequence of this interaction is believed to result in the incapacity of RNk polymerase II to of transcribe efficiently this region.

EXAMPLE 2 Detection of bt884 mRNA Processing

PCT patent publication WO 91/16432 shows that the low cytoplasmic bt884 mRNA levels in tobacco are due to a limited flow rate of full length bt884 mRNA to the cytoplasm. The run-on analysis in combination with the deletion analysis described in PCT publication WO 91/16432 show that cryIAb transcript elongation in N28-220 is hindered between or close to nucleotides 700 and 1000, downstream of the start site of transcription initiation and that either several regions of the cryIAb coding region are involved in this process or transcriptional pausing at a cryptic promoter is not the sole process which interferes with expression.

To determine whether other processes are interfering with cytoplasmic bt884 mRNA accumulation, the integrity of the polyadenylated bt884 transcripts expressed by N28-220 was analyzed. The bt884 mRNA accumulates at levels which are below the detection limit of conventional Northern blot analyses of total RNA (Vaeck et al, 1987). The bt884 mRNA expressed by N28-220 was therefore studied as follows.

Mesophyll protoplasts of N28-220 were prepared as described by Denecke et al (1989). Total RNA was extracted according to Jones et al (1985), and a cDNA reaction was carried out using, as a DNA primer, oligo(dT) essentially as described by Kawasaki (1990). The first strand was used to amplify a specific DNA fragment employing the Polymerase Chain Reaction (PCR) as described by Kawasaki (1990) using the following sets of primers:

set A: PS66 and PS64,

set B: PS63 and PS65,

set C: PS58 and PS59,

set D: PS61 and PS62,

the primers being shown in the sequence listing as follows:

PS58 in SEQ ID NO. 10, PS59 in SEQ ID NO. 11, PS61 in SEQ ID NO. 13, PS62 in SEQ ID NO. 13, PS63 in SEQ ID NO. 14, PS64 in SEQ ID NO. 15, PS65 in SEQ ID NO. 16, and PS66 in SEQ ID NO. 17.

The amplified DNA products were run on a nondenaturing polyacrylamide gel, and primer sets k and B yielded DNA fragments of the expected size (FIG. 3a). Primer set C yielded, in addition to the expected DNA fragments, two additional DNA species of smaller size (II and III in FIG. 3b). Sequence analysis (Maxam and Gilbert, 1980) of the DNA fragments generated by primer set C revealed the presence of one and two deletions in the amplified bt884 DNA sequences II and III, respectively. The nucleotide sequences of the extremities of the deleted portions are in agreement with the sequences of consensus sites of plant intron borders of Hanley and Schuler (1988) i.e., GT at the 5' end of each deleted portion and AG at the 3' end of each deleted portion (FIG. 3b). The size of the deletions was respectively 208 and 139 nucleotides. Primer ser D yielded in addition to the expected DNA product, four smaller PCR products. Sequence analysis of these fragments confirmed the occurrence of the 208 nucleotides deletion and the combination of the 208 and 139 nucleotides deletion as was seen with the cDNA-PCR analysis using primer set C, as well as the combination of the 208 nucleotides and a novel 929 nucleotides deletion. The extremities of this latter deleted sequence agree with the consensus sites of 5' and 3' RNA splice sites. The deletions thus reveal that the bt884 precursor mRNk undergoes splicing, the exact location of two of its cryptic introns is shown in FIG. 3b. The introns in FIG. 3b, at position 1339 to 1477 and position 1579 to 1786, relative to the translation start site, were named "intron 1" and "intron 2", respectively. The intron at position 549 to 1477 was named "intron 3".

EXAMPLE 3 Construction of Modified Bt ICP Genes

The bt2 coding region, which has been modified in PCT publication WO 91/16432, was either the bt884 or bt860-neo coding region (Hofte et al, 1986; Vaeck et al, 1987). One example of such a modified bt2 coding region is the cryIAb6 coding region, which is derived from the bt884 coding region (Hofte et al, 1986) and has been modified (with the purpose to restore the elongation efficiency) between its nucleotides 590 (Xbal site) and 917 (EcoR: site), affecting 63 of the 107 codons within this fragment.

In a similar way, the CCAAT boxes at nucleotides 772 and 789 of the bt884 coding sequence (in plasmid pJD884) are specifically removed to demonstrate that these process-directing sequence elements are involved in inhibition of transcript elongation. The oligonucleotides RVA-5 and RVA-6 are used: to modify the proximal CCAAT box by changing its A at position 774 into a G; and to modify the proximal CCAAT box by changing its A at position 792 into a G or by changing its A and T at positions 792 and 793 into a G and C, respectively. The resulting construct changed at positions 774 and 792 is called "pRVA0201", and the resulting construct changed at positions 774, 792 and 793 is called "pRVA0202". RVA-5 is a mixture of oligonucleotides of SEQ ID NO. 18 and SEQ ID NO. 19; and RVA-6 is a mixture of the oligonucleotides of SEQ ID NO. 20 and 21, that are complementary to RVA-5.

The PCR-mediated mutagenesis procedure described by Ho et al (1989) is used to incorporate the nucleotide sequences of the RVA-5 and RVA-6 fragments into a 1091 bp Spel-EcoNI fragment of bt884 to change its CCAAT boxes at nucleotides 772 and 789. pRVA0201 and pRVA0202 are then introduced by electroporation into tobacco SR1 protoplasts for expression evaluation. Gene expression is found to be significantly improved.

The cryptic introns in the bt884 mRNA located at positions 1339-1477 (intron 1), 1579-1786 (intron 2) and 549-1477 (intron 3), relative to the translation start site, are functionally removed by the introduction of translationally neutral base substitutions at the appropriate positions in the bt884 coding region. The mutations are chosen such that the cryptic intron splice sites present on the bt884 coding region, which are necessary for the occurrence of splicing, become non-functional. Specifically, the 5' splice site of intron 1 was changed from AGT:GTAAGT into TCT:GTAACG, the 5' splice site of intron 2 was changed from CGG:GTAAGA into CGT:GTCCGG, and the 5' splice site of intron 3 was changed from AAG:GTGGGG into GCG:CTGGGG. The modifications were introduced each independently into plasmid pRVA0214 that carries the cryIAb22 gene. This gene is a derivative of bt884 that lacks the first 28 codons and has a GCU codon following the translation start signal. Furthermore, plasmid pRVA0214, which is derived from pJD884 (SEQ ID NO. 22), carries a chimeric cat reporter gene that serves as an experimental internal control in transient expression assays (Denecke et al, 1989). In a next step, the different 5' splice site modifications were combined resulting in a series of pRVA0214 derivatives carrying cryIAb genes with a modified 5' splice site of intron 1; intron 1 and 2; intron 1 and 3; intron 1, 2 and 3; intron 2; intron 2 and 3; and intron 3.

The plasmids were introduced into SR1 mesophyll protoplasts and 7 hours after delivery the expression of the different modified cry genes and of the cat gene was measured at the mRNA and protein level. An overview of the data is given in Table 1.

These data show that the genes modified at the 5' splice site of intron 2 give the highest ICP expression. When combined with modification in the 5' splice sites of intron 1 and 3, ICP expression further improves.

The relative ICP production rate was determined essentially as described by Denecke et al (1989, Table 2). This revealed that the splice site modifications greatly improve ICP production in time. In addition, a derivative of the cryIAb6 gene was made that carries the modified 5' splice sites of intron 2. Expression of this gene (cryIAb14) was compared with cryIAb6 at the mRNA and protein synthesis level. As shown in Table 2, the modification of the 5' splice site of intron 2, results in increased RNA level and greatly improves the ICP production level.

Taken together, these data demonstrate that the cryptic introns in bt884, particularly intron I and II, even more particularly intron II, cause abortive splicing of the bt884 precursor mRNA.

EXAMPLE 4 Cloning and Expression of Modified Bt ICP Genes in Tobacco and Potato Plants

Using the procedures described in U.S. patent application 821,582, filed Jan. 2, 1986, and EPA 86300291.1, EPA 88402115.5 and EPA 89400428.2, the modified Bt ICP (i.e., bt2) genes of Example 3 are inserted into the intermediate T-DNA vector, pGSH1160 (Deblaere et al, 1988), between the vector's T-DNA terminal border repeat sequences.

To obtain significant expression in plants, the modified Bt ICP genes of Example 3 are placed under the control of either the 35S promoter or the TR2' promoter (PTR2--Velten et al, 1984) and are fused to the transcript 3' end formation and polyadenylation signals of the chalcone synthase gene or the g7 gene.

In addition, the translation initiation context or site is changed in accordance with the Josh consensus sequence (Joshi, 1987) in order to optimize the translation initiation in plant cells. To this end, an oligo duplex is introduced to create the sequence, shown in SEQ ID NO. 23 from position 7561 to 6, at the translation initiation site. In this way, an additional codon (i.e., GCT) coding for alanine is introduced. Additionally, KpnI and BstXI sites are created upstream of the ATG translation initiation codon.

Using standard procedures (Deblaere et al, 1985), the intermediate plant expression vectors, containing the modified Bt ICP gene, are transferred into the Agrobacterium strain C58C1 Rif (U.S. patent application 821,582; EPA 86300291.1) carrying the disarmed Ti-plasmid pGV2260 (Vaeck et al, 1987). Selection for spectinomycin resistance yields cointegrated plasmids, consisting of pGV2260 and the respective intermediate plant expression vectors. Each of these recombinant Agrobacterium strains is then used to transform different tobacco plant cells (Nicotiana tabacum) and potato plant cells (Solanum tuberosum) so that the modified Bt ICP genes are contained in, and expressed by, different tobacco and potato plant cells.

The transgenic tobacco plants containing the modified Bt ICP genes are analyzed with an ELISA assay. These plants are characterized by a significant increase in levels of Bt (bt2) proteins, compared to a transgenic tobacco plant containing a non-modified Bt ICP (bt2) gene.

The insecticidal activity of the expression products of the modified Bt ICP (bt2) genes in leaves of transformed tobacco and potato plants is evaluated by recording the growth rate and mortality of larvae of tobacco hornworm (Manduca sexta), tobacco budworm (Heliothic virescens) and potato tubermoth (Phthorimaea operculella) fed on leaves of these two types of plants. These results are compared with the growth rate of larvae fed leaves from tobacco and potato plants transformed with the unmodified or parental Bt ICP (bt2) gene and leaves from untransformed potato and tobacco plants. Toxicity assays are performed as described in EPA 88402115.5 and EPA 86300291.1.

The insecticidal activity of transgenic tobacco plants containing the modified Bt ICP genes is determined against second and third instar larvae of Heliothis virescens. The control plants were not transformed. A significantly higher mortality rate is obtained among larvae fed on leaves or transformed plants containing and expressing the modified Bt ICP genes. Tobacco and potato plants containing the modified Bt ICP genes show considerably higher expression levels of Bt ICPs compared to tobacco and potato plants containing the unmodified Bt ICP gene.

Needless to say, this invention is not limited to tobacco and potato plants transformed with the modified Bt ICP gene. It includes any plant, such as tomato, alfalfa, sunflowers, corn, cotton., soybean, sugar beets, rapeseed, brassicas and other vegetables, transformed with the modified Bt ICP gene.

Nor is the invention limited to the use of Agrobacterium tumefaciens Ti-plasmids for transforming plant cells with a modified Bt ICP gene. Other known techniques for plant transformation, such as by means of liposomes, by electroporation or by vector systems based on plant viruses or pollen, can be used for transforming monocotyledonous and dicotyledonous plants wish such a modified Bt ICP gene. In this regard, monocots, including economically important crops such as cereals, particularly corn and rice, can be efficiently transformed using the procedures described in WO 92/09696, in which compact embryogenic callus or intact tissue, from which such callus can be obtained, is wounded by cutting and/or enzymatic degradation and then is transformed, for example by means of electroporation of linear DNA molecules.

Nor is the invention limited to the bt2 gene but rather encompasses all CryI, CryII, CryIII and CryIV Bt ICP genes. Indeed, sequences which can be present in cryptic promoters, e.g. CCAAT sequences, are found on both DNA strands (i.e., coding and non-coding strands) in all Bt ICP genes. By way of example, the positions of different perfect CCAAT sequences are listed in Table 3 below for the cryIB (bt14) gene, cryIC (bt15) gene, cryIE (bt18) gene and cryIIID (bt109P) gene. If such CCAAT sequences are in the correct environment, they can function as a cryptic promoter and thus interfere with transcription.

Similarly, plant intron splice sites are found within the coding region of many Bt ICPs. By using the properties of this invention abortive introns can be identified in these genes.

                  TABLE 1     ______________________________________                                     REL. ICP LEVEL            MOD. 5' SPLICE           7 HRS AFTER     GENE   SITE        PLASMID NAME DELIVERY     ______________________________________     bt884  --          pJD884       1     crvIAb22            --          pRVA0214     3     crvIAb28            I           pRVA0219     4.3     crvIAb24            II          pRVA0218     8.4     crvIAb21            III         pRVA0213     3.2     crvIAb26            I, II       pRVA0220     9.2     crvIAb27            I, III      pRVA0216     4.2     crvIAb23            II, III     pRVA0217     8.5     crvIAb25            I, II, III  pRVA0215     9.4     ______________________________________

Relative protein levels were determined by ELISA and CAT activity assays. Protein values are not absolute but rather show a general trend. The genes cryIAb28, -24, -21, -26, -27, -23, and -25 are derived from the cryIAb22 gene.

                  TABLE 2     ______________________________________            MOD. 5'            SPLICE                        REL. ICP     GENE   SITE     PLASMID NAME ΔICP/hr                                          mRNA level     ______________________________________     bt884  --       pJD884          1 ± 0.25                                          ND     crvIAb22            --       pRVA0214      7 ± 2                                          ND     crvIAb24            II       pRVA0218     12 ± 4                                          ND     crvIAb23            II, III  pRVA0217     17 ± 5                                          ND     crvIAb26            I, II    pRVA0220     24 ± 3                                          ND     crvIAb6            --       pPS0212      17 ± 3                                          1.3 ± 0.3     crvIAb14            II       pRVA0208     37 ± 2                                          3.9 ± 0.6     ______________________________________

relative bt mRNA levels in total RNA of transiently transformed tobacco leaf protoplasts was determined 7 hrs after plasmid delivery corrected for cat mRNA levels essentially as described by Cornelissen and Vandewiele (1989b). .increment.ICP/hr is the relative ICP accumulation rate per hour corrected for the CAT accumulation rate per hour (ND: not determined).

ICP/CAT values were determined as described in patent publication no WO 91/16432. Time point samples were taken 0, 3.5, 7, 11 and 20 hrs after plasmid delivery. RNA and protein values are not absolute but rather show a general trend.

the genes cryIAb24, 23, and 26 are derived from cryIAb22, gene cryIAb14 is derived from cryIAb6.

                  TABLE 3     ______________________________________     DNA     Strands  bt14     bt15       bt18   bt109P     ______________________________________     5' -> 3' 453-457  491-495    148-152                                         937-941              823-827  763-767    763-767                                         1405-1409              1072-1076                       1539-1541  1234-1238                                         1870-1874              1112-1116                       1916-1920  1531-1535                                         1962-1966              1507-1511           1685-1689     3' -> 5' 192-196  671-675    943-947                                         456-461              404-408  935-939    1492-1496                                         668-672              871-875  962-966    1648-1496                                         1091-1095              905-909  1759-1763         1918-1922              1042-1046              1480-1484     ______________________________________

The positions of other inhibitory sequences that can interact with CCAAT binding proteins are not listed in Table 3.

REFERENCES

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    __________________________________________________________________________     #             SEQUENCE LISTING     - (1) GENERAL INFORMATION:     -    (iii) NUMBER OF SEQUENCES: 23     - (2) INFORMATION FOR SEQ ID NO:1:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 26 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS48     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:     #              26  ACAA TACGGG     - (2) INFORMATION FOR SEQ ID NO:2:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS43     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:     #            29    CTTC TATGCCCTG     - (2) INFORMATION FOR SEQ ID NO:3:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 24 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS38     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:     #                24AGAA TCTG     - (2) INFORMATION FOR SEQ ID NO:4:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 11 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS39     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:     #       11     - (2) INFORMATION FOR SEQ ID NO:5:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 25 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS47     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:     #               25 ATTA GAGCG     - (2) INFORMATION FOR SEQ ID NO:6:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 26 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS44     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:     #              26  CCGA GCCTCG     - (2) INFORMATION FOR SEQ ID NO:7:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 24 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS38     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:     #                24AGAA TCTG     - (2) INFORMATION FOR SEQ ID NO:8:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 26 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS46     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:     #              26  GTAT GGGGAC     - (2) INFORMATION FOR SEQ ID NO:9:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 23 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS45     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:     #                23TACC ATC     - (2) INFORMATION FOR SEQ ID NO:10:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS58     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:     #            29    GATT TAGTCATCG     - (2) INFORMATION FOR SEQ ID NO:11:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS59     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:     #            29    CTGC TAGAGCCGG     - (2) INFORMATION FOR SEQ ID NO:12:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS61     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:     #            29    AAGA CTGAGTGCG     - (2) INFORMATION FOR SEQ ID NO:13:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS62     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:     #            29    CTTG TCGCTAACG     - (2) INFORMATION FOR SEQ ID NO:14:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS63     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:     #            29    ATTT GATGCCGCG     - (2) INFORMATION FOR SEQ ID NO:15:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS64     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:     #            29    CGCT CTAATCCCG     - (2) INFORMATION FOR SEQ ID NO:16:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS65     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:     #            29    CTAA ATCCTTGCC     - (2) INFORMATION FOR SEQ ID NO:17:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 29 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as PS66     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:     #            29    CGAT AACAATCCG     - (2) INFORMATION FOR SEQ ID NO:18:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 37 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as RVA-5a     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:     #      37          CAGT TTCCCAGTTA ACAAGAG     - (2) INFORMATION FOR SEQ ID NO:19:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 37 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as RVA-5b     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19:     #      37          CAGT TTCCCAGCTA ACAAGAG     - (2) INFORMATION FOR SEQ ID NO:20:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 37 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as RVA-6a     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:20:     #      37          AACT GTTCGAATCG GATACGT     - (2) INFORMATION FOR SEQ ID NO:21:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 37 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: single               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: oligonucleot - #ide, designated as RVA-6b     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:21:     #      37          AACT GTTCGAATCG GATACGT     - (2) INFORMATION FOR SEQ ID NO:22:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 7639 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: double               (D) TOPOLOGY: circular     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: plasmid D - #NA designated as pJD884     -     (ix) FEATURE:               (A) NAME/KEY: CDS               (B) LOCATION: 1..1869     #/note= "Coding region of aTION:                   truncated bt2 - # (cryIAb) gene, also designated as the     bt884                   gene."     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 1877..2110     #/note= "3' regulatory sequence:                   containing th - #e polyadenylation site derived from     #T-DNA gene 7."grobacterium     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 2480..3005     #/note= "35S promoter sequenceN:     #Cauliflower mosaic virus."     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 3006..3665     #/note= "Coding sequence ofTION:     #acetyl transferase gene."col     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 3666..4491     #/note= "3' regulatory sequence:                   containing th - #e polyadenylation site derived from     #T-DNA octopine synthase gene."     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 5684..6541     #/note= "Sequence complementary to     #sequence of the beta-lactamase gene."     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 7155..7639     #/note= "TR1' and TR2' promoter:     #Agrobacterium T-DNA."from     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:22:     - ATG GAT CCC GAT AAC AAT CCG AAC ATC AAT GA - #A TGC ATT CCT TAT AAT       48     Met Asp Pro Asp Asn Asn Pro Asn Ile Asn Gl - #u Cys Ile Pro Tyr Asn     #                 15     - TGT TTA AGT AAC CCT GAA GTA GAA GTA TTA GG - #T GGA GAA AGA ATA GAA       96     Cys Leu Ser Asn Pro Glu Val Glu Val Leu Gl - #y Gly Glu Arg Ile Glu     #             30     - ACT GGT TAC ACC CCA ATC GAT ATT TCC TTG TC - #G CTA ACG CAA TTT CTT      144     Thr Gly Tyr Thr Pro Ile Asp Ile Ser Leu Se - #r Leu Thr Gln Phe Leu     #         45     - TTG AGT GAA TTT GTT CCC GGT GCT GGA TTT GT - #G TTA GGA CTA GTT GAT      192     Leu Ser Glu Phe Val Pro Gly Ala Gly Phe Va - #l Leu Gly Leu Val Asp     #     60     - ATA ATA TGG GGA ATT TTT GGT CCC TCT CAA TG - #G GAC GCA TTT CTT GTA      240     Ile Ile Trp Gly Ile Phe Gly Pro Ser Gln Tr - #p Asp Ala Phe Leu Val     # 80     - CAA ATT GAA CAG TTA ATT AAC CAA AGA ATA GA - #A GAA TTC GCT AGG AAC      288     Gln Ile Glu Gln Leu Ile Asn Gln Arg Ile Gl - #u Glu Phe Ala Arg Asn     #                 95     - CAA GCC ATT TCT AGA TTA GAA GGA CTA AGC AA - #T CTT TAT CAA ATT TAC      336     Gln Ala Ile Ser Arg Leu Glu Gly Leu Ser As - #n Leu Tyr Gln Ile Tyr     #           110     - GCA GAA TCT TTT AGA GAG TGG GAA GCA GAT CC - #T ACT AAT CCA GCA TTA      384     Ala Glu Ser Phe Arg Glu Trp Glu Ala Asp Pr - #o Thr Asn Pro Ala Leu     #       125     - AGA GAA GAG ATG CGT ATT CAA TTC AAT GAC AT - #G AAC AGT GCC CTT ACA      432     Arg Glu Glu Met Arg Ile Gln Phe Asn Asp Me - #t Asn Ser Ala Leu Thr     #   140     - ACC GCT ATT CCT CTT TTT GCA GTT CAA AAT TA - #T CAA GTT CCT CTT TTA      480     Thr Ala Ile Pro Leu Phe Ala Val Gln Asn Ty - #r Gln Val Pro Leu Leu     145                 1 - #50                 1 - #55                 1 -     #60     - TCA GTA TAT GTT CAA GCT GCA AAT TTA CAT TT - #A TCA GTT TTG AGA GAT      528     Ser Val Tyr Val Gln Ala Ala Asn Leu His Le - #u Ser Val Leu Arg Asp     #               175     - GTT TCA GTG TTT GGA CAA AGG TGG GGA TTT GA - #T GCC GCG ACT ATC AAT      576     Val Ser Val Phe Gly Gln Arg Trp Gly Phe As - #p Ala Ala Thr Ile Asn     #           190     - AGT CGT TAT AAT GAT TTA ACT AGG CTT ATT GG - #C AAC TAT ACA GAT CAT      624     Ser Arg Tyr Asn Asp Leu Thr Arg Leu Ile Gl - #y Asn Tyr Thr Asp His     #       205     - GCT GTA CGC TGG TAC AAT ACG GGA TTA GAG CG - #T GTA TGG GGA CCG GAT      672     Ala Val Arg Trp Tyr Asn Thr Gly Leu Glu Ar - #g Val Trp Gly Pro Asp     #   220     - TCT AGA GAT TGG ATA AGA TAT AAT CAA TTT AG - #A AGA GAA TTA ACA CTA      720     Ser Arg Asp Trp Ile Arg Tyr Asn Gln Phe Ar - #g Arg Glu Leu Thr Leu     225                 2 - #30                 2 - #35                 2 -     #40     - ACT GTA TTA GAT ATC GTT TCT CTA TTT CCG AA - #C TAT GAT AGT AGA ACG      768     Thr Val Leu Asp Ile Val Ser Leu Phe Pro As - #n Tyr Asp Ser Arg Thr     #               255     - TAT CCA ATT CGA ACA GTT TCC CAA TTA ACA AG - #A GAA ATT TAT ACA AAC      816     Tyr Pro Ile Arg Thr Val Ser Gln Leu Thr Ar - #g Glu Ile Tyr Thr Asn     #           270     - CCA GTA TTA GAA AAT TTT GAT GGT AGT TTT CG - #A GGC TCG GCT CAG GGC      864     Pro Val Leu Glu Asn Phe Asp Gly Ser Phe Ar - #g Gly Ser Ala Gln Gly     #       285     - ATA GAA GGA AGT ATT AGG AGT CCA CAT TTG AT - #G GAT ATA CTT AAC AGT      912     Ile Glu Gly Ser Ile Arg Ser Pro His Leu Me - #t Asp Ile Leu Asn Ser     #   300     - ATA ACC ATC TAT ACG GAT GCT CAT AGA GGA GA - #A TAT TAT TGG TCA GGG      960     Ile Thr Ile Tyr Thr Asp Ala His Arg Gly Gl - #u Tyr Tyr Trp Ser Gly     305                 3 - #10                 3 - #15                 3 -     #20     - CAT CAA ATA ATG GCT TCT CCT GTA GGG TTT TC - #G GGG CCA GAA TTC ACT     1008     His Gln Ile Met Ala Ser Pro Val Gly Phe Se - #r Gly Pro Glu Phe Thr     #               335     - TTT CCG CTA TAT GGA ACT ATG GGA AAT GCA GC - #T CCA CAA CAA CGT ATT     1056     Phe Pro Leu Tyr Gly Thr Met Gly Asn Ala Al - #a Pro Gln Gln Arg Ile     #           350     - GTT GCT CAA CTA GGT CAG GGC GTG TAT AGA AC - #A TTA TCG TCC ACT TTA     1104     Val Ala Gln Leu Gly Gln Gly Val Tyr Arg Th - #r Leu Ser Ser Thr Leu     #       365     - TAT AGA AGA CCT TTT AAT ATA GGG ATA AAT AA - #T CAA CAA CTA TCT GTT     1152     Tyr Arg Arg Pro Phe Asn Ile Gly Ile Asn As - #n Gln Gln Leu Ser Val     #   380     - CTT GAC GGG ACA GAA TTT GCT TAT GGA ACC TC - #C TCA AAT TTG CCA TCC     1200     Leu Asp Gly Thr Glu Phe Ala Tyr Gly Thr Se - #r Ser Asn Leu Pro Ser     385                 3 - #90                 3 - #95                 4 -     #00     - GCT GTA TAC AGA AAA AGC GGA ACG GTA GAT TC - #G CTG GAT GAA ATA CCG     1248     Ala Val Tyr Arg Lys Ser Gly Thr Val Asp Se - #r Leu Asp Glu Ile Pro     #               415     - CCA CAG AAT AAC AAC GTG CCA CCT AGG CAA GG - #A TTT AGT CAT CGA TTA     1296     Pro Gln Asn Asn Asn Val Pro Pro Arg Gln Gl - #y Phe Ser His Arg Leu     #           430     - AGC CAT GTT TCA ATG TTT CGT TCA GGC TTT AG - #T AAT AGT AGT GTA AGT     1344     Ser His Val Ser Met Phe Arg Ser Gly Phe Se - #r Asn Ser Ser Val Ser     #       445     - ATA ATA AGA GCT CCT ATG TTC TCT TGG ATA CA - #T CGT AGT GCT GAA TTT     1392     Ile Ile Arg Ala Pro Met Phe Ser Trp Ile Hi - #s Arg Ser Ala Glu Phe     #   460     - AAT AAT ATA ATT CCT TCA TCA CAA ATT ACA CA - #A ATA CCT TTA ACA AAA     1440     Asn Asn Ile Ile Pro Ser Ser Gln Ile Thr Gl - #n Ile Pro Leu Thr Lys     465                 4 - #70                 4 - #75                 4 -     #80     - TCT ACT AAT CTT GGC TCT GGA ACT TCT GTC GT - #T AAA GGA CCA GGA TTT     1488     Ser Thr Asn Leu Gly Ser Gly Thr Ser Val Va - #l Lys Gly Pro Gly Phe     #               495     - ACA GGA GGA GAT ATT CTT CGA AGA ACT TCA CC - #T GGC CAG ATT TCA ACC     1536     Thr Gly Gly Asp Ile Leu Arg Arg Thr Ser Pr - #o Gly Gln Ile Ser Thr     #           510     - TTA AGA GTA AAT ATT ACT GCA CCA TTA TCA CA - #A AGA TAT CGG GTA AGA     1584     Leu Arg Val Asn Ile Thr Ala Pro Leu Ser Gl - #n Arg Tyr Arg Val Arg     #       525     - ATT CGC TAC GCT TCT ACC ACA AAT TTA CAA TT - #C CAT ACA TCA ATT GAC     1632     Ile Arg Tyr Ala Ser Thr Thr Asn Leu Gln Ph - #e His Thr Ser Ile Asp     #   540     - GGA AGA CCT ATT AAT CAG GGG AAT TTT TCA GC - #A ACT ATG AGT AGT GGG     1680     Gly Arg Pro Ile Asn Gln Gly Asn Phe Ser Al - #a Thr Met Ser Ser Gly     545                 5 - #50                 5 - #55                 5 -     #60     - AGT AAT TTA CAG TCC GGA AGC TTT AGG ACT GT - #A GGT TTT ACT ACT CCG     1728     Ser Asn Leu Gln Ser Gly Ser Phe Arg Thr Va - #l Gly Phe Thr Thr Pro     #               575     - TTT AAC TTT TCA AAT GGA TCA AGT GTA TTT AC - #G TTA AGT GCT CAT GTC     1776     Phe Asn Phe Ser Asn Gly Ser Ser Val Phe Th - #r Leu Ser Ala His Val     #           590     - TTC AAT TCA GGC AAT GAA GTT TAT ATA GAT CG - #A ATT GAA TTT GTT CCG     1824     Phe Asn Ser Gly Asn Glu Val Tyr Ile Asp Ar - #g Ile Glu Phe Val Pro     #       605     - GCA GAA GTA ACC TTC GAC CTG CAG CCA AGC TT - #G CTG ATT GAT TGA     1869     Ala Glu Val Thr Phe Asp Leu Gln Pro Ser Le - #u Leu Ile Asp  *     #   620     - CCGGATCGAT CCGGCTCTAG CAGATCCCCC GATGAGCTAA GCTAGCTATA TC - #ATCAATTT     1929     - ATGTATTACA CATAATATCG CACTCAGTCT TTCATCTACG GCAATGTACC AG - #CTGATATA     1989     - ATCAGTTATT GAAATATTTC TGAATTTAAA CTTGCATCAA TAAATTTATG TT - #TTTGCTTG     2049     - GACTATAATA CCTGACTTGT TATTTTATCA ATAAATATTT AAACTATATT TC - #TTTCAAGA     2109     - TGGGAATTAA CATCTACAAA TTGCCTTTTC TTATCGACCA TGTACGGGTA CC - #GAGCTCGA     2169     - ATTCCTACGC AGCAGGTCTC ATCAAGACGA TCTACCCGAG TAACAATCTC CA - #GGAGATCA     2229     - AATACCTTCC CAAGAAGGTT AAAGATGCAG TCAAAAGATT CAGGACTAAT TG - #CATCAAGA     2289     - ACACAGAGAA AGACATATTT CTCAAGATCA GAAGTACTAT TCCAGTATGG AC - #GATTCAAG     2349     - GCTTGCTTCA TAAACCAAGG CAAGTAATAG AGATTGGAGT CTCTAAAAAG GT - #AGTTCCTA     2409     - CTGAATCTAA GGCCATGCAT GGAGTCTAAG ATTCAAATCG AGGATCTAAC AG - #AACTCGCC     2469     - GTGAAGACTG GCGAACAGTT CATACAGAGT CTTTTACGAC TCAATGACAA GA - #AGAAAATC     2529     - TTCGTCAACA TGGTGGAGCA CGACACTCTG GTCTACTCCA AAAATGTCAA AG - #ATACAGTC     2589     - TCAGAAGACC AAAGGGCTAT TGAGACTTTT CAACAAAGGA TAATTTCGGG AA - #ACCTCCTC     2649     - GGATTCCATT GCCCAGCTAT CTGTCACTTC ATCGAAAGGA CAGTAGAAAA GG - #AAGGTGGC     2709     - TCCTACAAAT GCCATCATTG CGATAAAGGA AAGGCTATCA TTCAAGATGC CT - #CTGCCGAC     2769     - AGTGGTCCCA AAGATGGACC CCCACCCACG AGGAGCATCG TGGAAAAAGA AG - #ACGTTCCA     2829     - ACCACGTCTT CAAAGCAAGT GGATTGATGT GACATCTCCA CTGACGTAAG GG - #ATGACGCA     2889     - CAATCCCACT ATCCTTCGCA AGACCCTTCC TCTATATAAG GAAGTTCATT TC - #ATTTGGAG     2949     - AGGACACGCT GAAATCACCA GTCTCTCTCT ATAAATCTAT CTCTCTCTCT AT - #AACCATGG     3009     - AGAAAAAAAT CACTGGATAT ACCACCGTTG ATATATCCCA ATGGCATCGT AA - #AGAACATT     3069     - TTGAGGCATT TCAGTCAGTT GCTCAATGTA CCTATAACCA GACCGTTCAG CT - #GGATATTA     3129     - CGGCCTTTTT AAAGACCGTA AAGAAAAATA AGCACAAGTT TTATCCGGCC TT - #TATTCACA     3189     - TTCTTGCCCG CCTGATGAAT GCTCATCCGG AATTCCGTAT GGCAATGAAA GA - #CGGTGAGC     3249     - TGGTGATATG GGATAGTGTT CACCCTTGTT ACACCGTTTT CCATGAGCAA AC - #TGAAACGT     3309     - TTTCATCGCT CTGGAGTGAA TACCACGACG ATTTCCGGCA GTTTCTACAC AT - #ATATTCGC     3369     - AAGATGTGGC GTGTTACGGT GAAAACCTGG CCTATTTCCC TAAAGGGTTT AT - #TGAGAATA     3429     - TGTTTTTCGT CTCAGCCAAT CCCTGGGTGA GTTTCACCAG TTTTGATTTA AA - #CGTGGCCA     3489     - ATATGGACAA CTTCTTCGCC CCCGTTTTCA CCATGGGCAA ATATTATACG CA - #AGGCGACA     3549     - AGGTGCTGAT GCCGCTGGCG ATTCAGGTTC ATCATGCCGT CTGTGATGGC TT - #CCATGTCG     3609     - GCAGAATGCT TAATGAATTA CAACAGTACT GCGATGAGTG GCAGGGCGGG GC - #GTAATTTT     3669     - TTTAAGGCAG TTATTGGTGC CCTTAAACGC CTGGTTGCTA CGCCTGAATA AG - #TGATAATA     3729     - AGCGGATGAA TGGCAGAAAT TCGAAAGCAA ATTCGACCCA TCGCGCGTCT AG - #AGTCCTGC     3789     - TTTAATGAGA TATGCGAGAC GCCTATGATC GCATGATATT TGCTTTCAAT TC - #TGTTGTGC     3849     - ACGTTGTAAA AAACCTGAGC ATGTGTAGCT CAGATCCTTA CCGCCGGTTT CG - #GTTCATTC     3909     - TAATGAATAT ATCACCCGTT ACTATCGTAT TTTTATGAAT AATATTCTCC GT - #TCAATTTA     3969     - CTGATTGTAC CCTACTACTT ATATGTACAA TATTAAAATG AAAACAATAT AT - #TGTGCTGA     4029     - ATAGGTTTAT AGCGACATCT ATGATAGAGC GCCACAATAA CAAACAATTG CG - #TTTTATTA     4089     - TTACAAATCC AATTTTAAAA AAAGCGGCAG AACCGGTCAA ACCTAAAAGA CT - #GATTACAT     4149     - AAATCTTATT CAAATTTCAA AAGGCCCCAG GGGCTAGTAT CTACGACACA CC - #GAGCGGCG     4209     - AACTAATAAC GTTCACTGAA GGGAACTCCG GTTCCCCGCC GGCGCGCATG GG - #TGAGATTC     4269     - CTTGAAGTTG AGTATTGGCC GTCCGCTCTA CCGAAAGTTA CGGGCACCAT TC - #AACCCGGT     4329     - CCAGCACGGC GGCCGGGTAA CCGACTTGCT GCCCCGAGAA TTATGCAGCA TT - #TTTTTGGT     4389     - GTATGTGGGC CCCAAATGAA GTGCAGGTCA AACCTTGACA GTGACGACAA AT - #CGTTGGGC     4449     - GGGTCCAGGG CGAATTTTGC GACAACATGT CGAGGCTCAG CAGGACCTGC AG - #GAATTCGG     4509     - CGTAATCATG GTCATAGCTG TTTCCTGTGT GAAATTGTTA TCCGCTCACA AT - #TCCACACA     4569     - ACATACGAGC CGGAAGCATA AAGTGTAAAG CCTGGGGTGC CTAATGAGTG AG - #CTAACTCA     4629     - CATTAATTGC GTTGCGCTCA CTGCCCGCTT TCCAGTCGGG AAACCTGTCG TG - #CCAGCTGC     4689     - ATTAATGAAT CGGCCAACGC GCGGGGAGAG GCGGTTTGCG TATTGGGCGC TC - #TTCCGCTT     4749     - CCTCGCTCAC TGACTCGCTG CGCTCGGTCG TTCGGCTGCG GCGAGCGGTA TC - #AGCTCACT     4809     - CAAAGGCGGT AATACGGTTA TCCACAGAAT CAGGGGATAA CGCAGGAAAG AA - #CATGTGAG     4869     - CAAAAGGCCA GCAAAAGGCC AGGAACCGTA AAAAGGCCGC GTTGCTGGCG TT - #TTTCCATA     4929     - GGCTCCGCCC CCCTGACGAG CATCACAAAA ATCGACGCTC AAGTCAGAGG TG - #GCGAAACC     4989     - CGACAGGACT ATAAAGATAC CAGGCGTTTC CCCCTGGAAG CTCCCTCGTG CG - #CTCTCCTG     5049     - TTCCGACCCT GCCGCTTACC GGATACCTGT CCGCCTTTCT CCCTTCGGGA AG - #CGTGGCGC     5109     - TTTCTCAATG CTCACGCTGT AGGTATCTCA GTTCGGTGTA GGTCGTTCGC TC - #CAAGCTGG     5169     - GCTGTGTGCA CGAACCCCCC GTTCAGCCCG ACCGCTGCGC CTTATCCGGT AA - #CTATCGTC     5229     - TTGAGTCCAA CCCGGTAAGA CACGACTTAT CGCCACTGGC AGCAGCCACT GG - #TAACAGGA     5289     - TTAGCAGAGC GAGGTATGTA GGCGGTGCTA CAGAGTTCTT GAAGTGGTGG CC - #TAACTACG     5349     - GCTACACTAG AAGGACAGTA TTTGGTATCT GCGCTCTGCT GAAGCCAGTT AC - #CTTCGGAA     5409     - AAAGAGTTGG TAGCTCTTGA TCCGGCAAAC AAACCACCGC TGGTAGCGGT GG - #TTTTTTTG     5469     - TTTGCAAGCA GCAGATTACG CGCAGAAAAA AAGGATCTCA AGAAGATCCT TT - #GATCTTTT     5529     - CTACGGGGTC TGACGCTCAG TGGAACGAAA ACTCACGTTA AGGGATTTTG GT - #CATGAGAT     5589     - TATCAAAAAG GATCTTCACC TAGATCCTTT TAAATTAAAA ATGAAGTTTT AA - #ATCAATCT     5649     - AAAGTATATA TGAGTAAACT TGGTCTGACA GTTACCAATG CTTAATCAGT GA - #GGCACCTA     5709     - TCTCAGCGAT CTGTCTATTT CGTTCATCCA TAGTTGCCTG ACTCCCCGTC GT - #GTAGATAA     5769     - CTACGATACG GGAGGGCTTA CCATCTGGCC CCAGTGCTGC AATGATACCG CG - #AGACCCAC     5829     - GCTCACCGGC TCCAGATTTA TCAGCAATAA ACCAGCCAGC CGGAAGGGCC GA - #GCGCAGAA     5889     - GTGGTCCTGC AACTTTATCC GCCTCCATCC AGTCTATTAA TTGTTGCCGG GA - #AGCTAGAG     5949     - TAAGTAGTTC GCCAGTTAAT AGTTTGCGCA ACGTTGTTGC CATTGCTACA GG - #CATCGTGG     6009     - TGTCACGCTC GTCGTTTGGT ATGGCTTCAT TCAGCTCCGG TTCCCAACGA TC - #AAGGCGAG     6069     - TTACATGATC CCCCATGTTG TGCAAAAAAG CGGTTAGCTC CTTCGGTCCT CC - #GATCGTTG     6129     - TCAGAAGTAA GTTGGCCGCA GTGTTATCAC TCATGGTTAT GGCAGCACTG CA - #TAATTCTC     6189     - TTACTGTCAT GCCATCCGTA AGATGCTTTT CTGTGACTGG TGAGTACTCA AC - #CAAGTCAT     6249     - TCTGAGAATA GTGTATGCGG CGACCGAGTT GCTCTTGCCC GGCGTCAATA CG - #GGATAATA     6309     - CCGCGCCACA TAGCAGAACT TTAAAAGTGC TCATCATTGG AAAACGTTCT TC - #GGGGCGAA     6369     - AACTCTCAAG GATCTTACCG CTGTTGAGAT CCAGTTCGAT GTAACCCACT CG - #TGCACCCA     6429     - ACTGATCTTC AGCATCTTTT ACTTTCACCA GCGTTTCTGG GTGAGCAAAA AC - #AGGAAGGC     6489     - AAAATGCCGC AAAAAAGGGA ATAAGGGCGA CACGGAAATG TTGAATACTC AT - #ACTCTTCC     6549     - TTTTTCAATA TTATTGAAGC ATTTATCAGG GTTATTGTCT CATGAGCGGA TA - #CATATTTG     6609     - AATGTATTTA GAAAAATAAA CAAATAGGGG TTCCGCGCAC ATTTCCCCGA AA - #AGTGCCAC     6669     - CTGACGTCTA AGAAACCATT ATTATCATGA CATTAACCTA TAAAAATAGG CG - #TATCACGA     6729     - GGCCCTTTCG TCTCGCGCGT TTCGGTGATG ACGGTGAAAA CCTCTGACAC AT - #GCAGCTCC     6789     - CGGAGACGGT CACAGCTTGT CTGTAAGCGG ATGCCGGGAG CAGACAAGCC CG - #TCAGGGCG     6849     - CGTCAGCGGG TGTTGGCGGG TGTCGGGGCT GGCTTAACTA TGCGGCATCA GA - #GCAGATTG     6909     - TACTGAGAGT GCACCATATG CGGTGTGAAA TACCGCACAG ATGCGTAAGG AG - #AAAATACC     6969     - GCATCAGGCG CCATTCGCCA TTCAGGCTGC GCAACTGTTG GGAAGGGCGA TC - #GGTGCGGG     7029     - CCTCTTCGCT ATTACGCCAG CTGGCGAAAG GGGGATGTGC TGCAAGGCGA TT - #AAGTTGGG     7089     - TAACGCCAGG GTTTTCCCAG TCACGACGTT GTAAAACGAC GGCCAGTAAG CT - #TGGCTGCA     7149     - GGTCGAGATC CACGTGTGGA AGATATGAAT TTTTTTGAGA AACTAGATAA GA - #TTAATGAA     7209     - TATCGGTGTT TTGGTTTTTT CTTGTGGCCG TCTTTGTTTA TATTGAGATT TT - #TCAAATCA     7269     - GTGCGCAAGA CGTGACGTAA GTATCTGAGC TAGTTTTTAT TTTTCTACTA AT - #TTGGTCGT     7329     - TTATTTCGGC GTGTAGGACA TGGCAACCGG GCCTGAATTT CGCGGGTATT CT - #GTTTCTAT     7389     - TCCAACTTTT TCTTGATCCG CAGCCATTAA CGACTTTTGA ATAGATACGC TG - #ACACGCCA     7449     - AGCCTCGCTA GTCAAAAGTG TACCAAACAA CGCTTTACAG CAAGAACGGA AT - #GCGCGTGA     7509     - CGCTCGCGGT GACGCCATTT CGCCTTTTCA GAAATGGATA AATAGCCTTG CT - #TCCTATTA     7569     - TATCTTCCCA AATTACCAAT ACATTACACT AGCATCTGAA TTTCATAACC AA - #TCTCGATA     7629     #      7639     - (2) INFORMATION FOR SEQ ID NO:23:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 7566 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: double               (D) TOPOLOGY: circular     -     (ii) MOLECULE TYPE: DNA (genomic)     -     (vi) ORIGINAL SOURCE:               (A) ORGANISM: plasmid D - #NA designated as pPS0212     -     (ix) FEATURE:               (A) NAME/KEY: CDS               (B) LOCATION: 1..1785     #/note= "Coding region of aTION:                   truncated mod - #ified bt2 (cryIAb) gene, also designated     as     #gene."       the cryIAb6     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 1793..2026     #/note= "3' regulatory sequence:                   containing th - #e polyadenylation site derived from     #T-DNA gene 7."grobacterium     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 2396..2921     #/note= "35S promoter sequenceN:     #Cauliflower mosaic virus."     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 2922..3581     #/note= "Coding sequence ofTION:     #acetyl transferase gene."col     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 3582..4407     #/note= "3' regulatory sequence:                   containing th - #e polyadenylation site derived from     #T-DNA octopine synthase gene."     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 5600..6457     #/note= "Sequence complementary to     #sequence of the beta-lactamase gene."     -     (ix) FEATURE:               (A) NAME/KEY: misc.sub.-- - #feature               (B) LOCATION: 7071..7566     #/note= "TR1' and TR2 promoterN:     #Agrobacterium T-DNA (with modified leader     #to sequence of pJD884 of SEQ ID NO. 22."     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:23:     - ATG GCT ATC GAG ACC GGT TAC ACC CCA ATC GA - #T ATT TCC TTG TCG CTA       48     Met Ala Ile Glu Thr Gly Tyr Thr Pro Ile As - #p Ile Ser Leu Ser Leu     #                 15     - ACG CAA TTT CTT TTG AGT GAA TTT GTT CCC GG - #T GCT GGA TTT GTG TTA       96     Thr Gln Phe Leu Leu Ser Glu Phe Val Pro Gl - #y Ala Gly Phe Val Leu     #             30     - GGA CTA GTT GAT ATA ATA TGG GGA ATT TTT GG - #T CCC TCT CAA TGG GAC      144     Gly Leu Val Asp Ile Ile Trp Gly Ile Phe Gl - #y Pro Ser Gln Trp Asp     #         45     - GCA TTT CTT GTA CAA ATT GAA CAG TTA ATT AA - #C CAA AGA ATA GAA GAA      192     Ala Phe Leu Val Gln Ile Glu Gln Leu Ile As - #n Gln Arg Ile Glu Glu     #     60     - TTC GCT AGG AAC CAA GCC ATT TCT AGA TTA GA - #A GGA CTA AGC AAT CTT      240     Phe Ala Arg Asn Gln Ala Ile Ser Arg Leu Gl - #u Gly Leu Ser Asn Leu     # 80     - TAT CAA ATT TAC GCA GAA TCT TTT AGA GAG TG - #G GAA GCA GAT CCT ACT      288     Tyr Gln Ile Tyr Ala Glu Ser Phe Arg Glu Tr - #p Glu Ala Asp Pro Thr     #                 95     - AAT CCA GCA TTA AGA GAA GAG ATG CGT ATT CA - #A TTC AAT GAC ATG AAC      336     Asn Pro Ala Leu Arg Glu Glu Met Arg Ile Gl - #n Phe Asn Asp Met Asn     #           110     - AGT GCC CTT ACA ACC GCT ATT CCT CTT TTT GC - #A GTT CAA AAT TAT CAA      384     Ser Ala Leu Thr Thr Ala Ile Pro Leu Phe Al - #a Val Gln Asn Tyr Gln     #       125     - GTT CCT CTT TTA TCA GTA TAT GTT CAA GCT GC - #A AAT TTA CAT TTA TCA      432     Val Pro Leu Leu Ser Val Tyr Val Gln Ala Al - #a Asn Leu His Leu Ser     #   140     - GTT TTG AGA GAT GTT TCA GTG TTT GGA CAA AG - #G TGG GGA TTT GAT GCC      480     Val Leu Arg Asp Val Ser Val Phe Gly Gln Ar - #g Trp Gly Phe Asp Ala     145                 1 - #50                 1 - #55                 1 -     #60     - GCG ACT ATC AAT AGT CGT TAT AAT GAT TTA AC - #T AGG CTT ATT GGC AAC      528     Ala Thr Ile Asn Ser Arg Tyr Asn Asp Leu Th - #r Arg Leu Ile Gly Asn     #               175     - TAT ACA GAT CAT GCT GTA CGC TGG TAC AAT AC - #G GGA TTA GAG CGT GTA      576     Tyr Thr Asp His Ala Val Arg Trp Tyr Asn Th - #r Gly Leu Glu Arg Val     #           190     - TGG GGA CCG GAT TCT AGA GAC TGG ATC AGG TA - #C AAC CAG TTC AGG AGG      624     Trp Gly Pro Asp Ser Arg Asp Trp Ile Arg Ty - #r Asn Gln Phe Arg Arg     #       205     - GAG TTA ACC CTA ACC GTG TTA GAC ATC GTG TC - #C CTA TTC CCG AAC TAC      672     Glu Leu Thr Leu Thr Val Leu Asp Ile Val Se - #r Leu Phe Pro Asn Tyr     #   220     - GAC AGC AGG ACG TAC CCA ATC CGA ACC GTG TC - #C CAG TTA ACC AGG GAG      720     Asp Ser Arg Thr Tyr Pro Ile Arg Thr Val Se - #r Gln Leu Thr Arg Glu     225                 2 - #30                 2 - #35                 2 -     #40     - ATC TAC ACC AAC CCA GTG TTA GAG AAC TTC GA - #C GGT AGC TTC CGA GGC      768     Ile Tyr Thr Asn Pro Val Leu Glu Asn Phe As - #p Gly Ser Phe Arg Gly     #               255     - TCG GCT CAG GGC ATC GAG GGA AGC ATC AGG AG - #C CCA CAC TTG ATG GAC      816     Ser Ala Gln Gly Ile Glu Gly Ser Ile Arg Se - #r Pro His Leu Met Asp     #           270     - ATC CTT AAC AGC ATC ACC ATC TAC ACG GAC GC - #T CAC AGG GGA GAG TAC      864     Ile Leu Asn Ser Ile Thr Ile Tyr Thr Asp Al - #a His Arg Gly Glu Tyr     #       285     - TAC TGG TCC GGG CAC CAG ATC ATG GCT TCC CC - #T GTG GGG TTC TCG GGG      912     Tyr Trp Ser Gly His Gln Ile Met Ala Ser Pr - #o Val Gly Phe Ser Gly     #   300     - CCA GAA TTC ACT TTT CCG CTA TAT GGA ACT AT - #G GGA AAT GCA GCT CCA      960     Pro Glu Phe Thr Phe Pro Leu Tyr Gly Thr Me - #t Gly Asn Ala Ala Pro     305                 3 - #10                 3 - #15                 3 -     #20     - CAA CAA CGT ATT GTT GCT CAA CTA GGT CAG GG - #C GTG TAT AGA ACA TTA     1008     Gln Gln Arg Ile Val Ala Gln Leu Gly Gln Gl - #y Val Tyr Arg Thr Leu     #               335     - TCG TCC ACT TTA TAT AGA AGA CCT TTT AAT AT - #A GGG ATA AAT AAT CAA     1056     Ser Ser Thr Leu Tyr Arg Arg Pro Phe Asn Il - #e Gly Ile Asn Asn Gln     #           350     - CAA CTA TCT GTT CTT GAC GGG ACA GAA TTT GC - #T TAT GGA ACC TCC TCA     1104     Gln Leu Ser Val Leu Asp Gly Thr Glu Phe Al - #a Tyr Gly Thr Ser Ser     #       365     - AAT TTG CCA TCC GCT GTA TAC AGA AAA AGC GG - #A ACG GTA GAT TCG CTG     1152     Asn Leu Pro Ser Ala Val Tyr Arg Lys Ser Gl - #y Thr Val Asp Ser Leu     #   380     - GAT GAA ATA CCG CCA CAG AAT AAC AAC GTG CC - #A CCT AGG CAA GGA TTT     1200     Asp Glu Ile Pro Pro Gln Asn Asn Asn Val Pr - #o Pro Arg Gln Gly Phe     385                 3 - #90                 3 - #95                 4 -     #00     - AGT CAT CGA TTA AGC CAT GTT TCA ATG TTT CG - #T TCA GGC TTT AGT AAT     1248     Ser His Arg Leu Ser His Val Ser Met Phe Ar - #g Ser Gly Phe Ser Asn     #               415     - AGT AGT GTA AGT ATA ATA AGA GCT CCT ATG TT - #C TCT TGG ATA CAT CGT     1296     Ser Ser Val Ser Ile Ile Arg Ala Pro Met Ph - #e Ser Trp Ile His Arg     #           430     - AGT GCT GAA TTT AAT AAT ATA ATT CCT TCA TC - #A CAA ATT ACA CAA ATA     1344     Ser Ala Glu Phe Asn Asn Ile Ile Pro Ser Se - #r Gln Ile Thr Gln Ile     #       445     - CCT TTA ACA AAA TCT ACT AAT CTT GGC TCT GG - #A ACT TCT GTC GTT AAA     1392     Pro Leu Thr Lys Ser Thr Asn Leu Gly Ser Gl - #y Thr Ser Val Val Lys     #   460     - GGA CCA GGA TTT ACA GGA GGA GAT ATT CTT CG - #A AGA ACT TCA CCT GGC     1440     Gly Pro Gly Phe Thr Gly Gly Asp Ile Leu Ar - #g Arg Thr Ser Pro Gly     465                 4 - #70                 4 - #75                 4 -     #80     - CAG ATT TCA ACC TTA AGA GTA AAT ATT ACT GC - #A CCA TTA TCA CAA AGA     1488     Gln Ile Ser Thr Leu Arg Val Asn Ile Thr Al - #a Pro Leu Ser Gln Arg     #               495     - TAT CGG GTA AGA ATT CGC TAC GCT TCT ACC AC - #A AAT TTA CAA TTC CAT     1536     Tyr Arg Val Arg Ile Arg Tyr Ala Ser Thr Th - #r Asn Leu Gln Phe His     #           510     - ACA TCA ATT GAC GGA AGA CCT ATT AAT CAG GG - #G AAT TTT TCA GCA ACT     1584     Thr Ser Ile Asp Gly Arg Pro Ile Asn Gln Gl - #y Asn Phe Ser Ala Thr     #       525     - ATG AGT AGT GGG AGT AAT TTA CAG TCC GGA AG - #C TTT AGG ACT GTA GGT     1632     Met Ser Ser Gly Ser Asn Leu Gln Ser Gly Se - #r Phe Arg Thr Val Gly     #   540     - TTT ACT ACT CCG TTT AAC TTT TCA AAT GGA TC - #A AGT GTA TTT ACG TTA     1680     Phe Thr Thr Pro Phe Asn Phe Ser Asn Gly Se - #r Ser Val Phe Thr Leu     545                 5 - #50                 5 - #55                 5 -     #60     - AGT GCT CAT GTC TTC AAT TCA GGC AAT GAA GT - #T TAT ATA GAT CGA ATT     1728     Ser Ala His Val Phe Asn Ser Gly Asn Glu Va - #l Tyr Ile Asp Arg Ile     #               575     - GAA TTT GTT CCG GCA GAA GTA ACC TTC GAC CT - #G CAG CCA AGC TTG CTG     1776     Glu Phe Val Pro Ala Glu Val Thr Phe Asp Le - #u Gln Pro Ser Leu Leu     #           590     - ATT GAT TGA CCGGATCGAT CCGGCTCTAG CAGATCCCCC GATGAGCTA - #A     1825     Ile Asp  *             595     - GCTAGCTATA TCATCAATTT ATGTATTACA CATAATATCG CACTCAGTCT TT - #CATCTACG     1885     - GCAATGTACC AGCTGATATA ATCAGTTATT GAAATATTTC TGAATTTAAA CT - #TGCATCAA     1945     - TAAATTTATG TTTTTGCTTG GACTATAATA CCTGACTTGT TATTTTATCA AT - #AAATATTT     2005     - AAACTATATT TCTTTCAAGA TGGGAATTAA CATCTACAAA TTGCCTTTTC TT - #ATCGACCA     2065     - TGTACGGGTA CCGAGCTCGA ATTCCTACGC AGCAGGTCTC ATCAAGACGA TC - #TACCCGAG     2125     - TAACAATCTC CAGGAGATCA AATACCTTCC CAAGAAGGTT AAAGATGCAG TC - #AAAAGATT     2185     - CAGGACTAAT TGCATCAAGA ACACAGAGAA AGACATATTT CTCAAGATCA GA - #AGTACTAT     2245     - TCCAGTATGG ACGATTCAAG GCTTGCTTCA TAAACCAAGG CAAGTAATAG AG - #ATTGGAGT     2305     - CTCTAAAAAG GTAGTTCCTA CTGAATCTAA GGCCATGCAT GGAGTCTAAG AT - #TCAAATCG     2365     - AGGATCTAAC AGAACTCGCC GTGAAGACTG GCGAACAGTT CATACAGAGT CT - #TTTACGAC     2425     - TCAATGACAA GAAGAAAATC TTCGTCAACA TGGTGGAGCA CGACACTCTG GT - #CTACTCCA     2485     - AAAATGTCAA AGATACAGTC TCAGAAGACC AAAGGGCTAT TGAGACTTTT CA - #ACAAAGGA     2545     - TAATTTCGGG AAACCTCCTC GGATTCCATT GCCCAGCTAT CTGTCACTTC AT - #CGAAAGGA     2605     - CAGTAGAAAA GGAAGGTGGC TCCTACAAAT GCCATCATTG CGATAAAGGA AA - #GGCTATCA     2665     - TTCAAGATGC CTCTGCCGAC AGTGGTCCCA AAGATGGACC CCCACCCACG AG - #GAGCATCG     2725     - TGGAAAAAGA AGACGTTCCA ACCACGTCTT CAAAGCAAGT GGATTGATGT GA - #CATCTCCA     2785     - CTGACGTAAG GGATGACGCA CAATCCCACT ATCCTTCGCA AGACCCTTCC TC - #TATATAAG     2845     - GAAGTTCATT TCATTTGGAG AGGACACGCT GAAATCACCA GTCTCTCTCT AT - #AAATCTAT     2905     - CTCTCTCTCT ATAACCATGG AGAAAAAAAT CACTGGATAT ACCACCGTTG AT - #ATATCCCA     2965     - ATGGCATCGT AAAGAACATT TTGAGGCATT TCAGTCAGTT GCTCAATGTA CC - #TATAACCA     3025     - GACCGTTCAG CTGGATATTA CGGCCTTTTT AAAGACCGTA AAGAAAAATA AG - #CACAAGTT     3085     - TTATCCGGCC TTTATTCACA TTCTTGCCCG CCTGATGAAT GCTCATCCGG AA - #TTCCGTAT     3145     - GGCAATGAAA GACGGTGAGC TGGTGATATG GGATAGTGTT CACCCTTGTT AC - #ACCGTTTT     3205     - CCATGAGCAA ACTGAAACGT TTTCATCGCT CTGGAGTGAA TACCACGACG AT - #TTCCGGCA     3265     - GTTTCTACAC ATATATTCGC AAGATGTGGC GTGTTACGGT GAAAACCTGG CC - #TATTTCCC     3325     - TAAAGGGTTT ATTGAGAATA TGTTTTTCGT CTCAGCCAAT CCCTGGGTGA GT - #TTCACCAG     3385     - TTTTGATTTA AACGTGGCCA ATATGGACAA CTTCTTCGCC CCCGTTTTCA CC - #ATGGGCAA     3445     - ATATTATACG CAAGGCGACA AGGTGCTGAT GCCGCTGGCG ATTCAGGTTC AT - #CATGCCGT     3505     - CTGTGATGGC TTCCATGTCG GCAGAATGCT TAATGAATTA CAACAGTACT GC - #GATGAGTG     3565     - GCAGGGCGGG GCGTAATTTT TTTAAGGCAG TTATTGGTGC CCTTAAACGC CT - #GGTTGCTA     3625     - CGCCTGAATA AGTGATAATA AGCGGATGAA TGGCAGAAAT TCGAAAGCAA AT - #TCGACCCA     3685     - TCGCGCGTCT AGAGTCCTGC TTTAATGAGA TATGCGAGAC GCCTATGATC GC - #ATGATATT     3745     - TGCTTTCAAT TCTGTTGTGC ACGTTGTAAA AAACCTGAGC ATGTGTAGCT CA - #GATCCTTA     3805     - CCGCCGGTTT CGGTTCATTC TAATGAATAT ATCACCCGTT ACTATCGTAT TT - #TTATGAAT     3865     - AATATTCTCC GTTCAATTTA CTGATTGTAC CCTACTACTT ATATGTACAA TA - #TTAAAATG     3925     - AAAACAATAT ATTGTGCTGA ATAGGTTTAT AGCGACATCT ATGATAGAGC GC - #CACAATAA     3985     - CAAACAATTG CGTTTTATTA TTACAAATCC AATTTTAAAA AAAGCGGCAG AA - #CCGGTCAA     4045     - ACCTAAAAGA CTGATTACAT AAATCTTATT CAAATTTCAA AAGGCCCCAG GG - #GCTAGTAT     4105     - CTACGACACA CCGAGCGGCG AACTAATAAC GTTCACTGAA GGGAACTCCG GT - #TCCCCGCC     4165     - GGCGCGCATG GGTGAGATTC CTTGAAGTTG AGTATTGGCC GTCCGCTCTA CC - #GAAAGTTA     4225     - CGGGCACCAT TCAACCCGGT CCAGCACGGC GGCCGGGTAA CCGACTTGCT GC - #CCCGAGAA     4285     - TTATGCAGCA TTTTTTTGGT GTATGTGGGC CCCAAATGAA GTGCAGGTCA AA - #CCTTGACA     4345     - GTGACGACAA ATCGTTGGGC GGGTCCAGGG CGAATTTTGC GACAACATGT CG - #AGGCTCAG     4405     - CAGGACCTGC AGGAATTCGG CGTAATCATG GTCATAGCTG TTTCCTGTGT GA - #AATTGTTA     4465     - TCCGCTCACA ATTCCACACA ACATACGAGC CGGAAGCATA AAGTGTAAAG CC - #TGGGGTGC     4525     - CTAATGAGTG AGCTAACTCA CATTAATTGC GTTGCGCTCA CTGCCCGCTT TC - #CAGTCGGG     4585     - AAACCTGTCG TGCCAGCTGC ATTAATGAAT CGGCCAACGC GCGGGGAGAG GC - #GGTTTGCG     4645     - TATTGGGCGC TCTTCCGCTT CCTCGCTCAC TGACTCGCTG CGCTCGGTCG TT - #CGGCTGCG     4705     - GCGAGCGGTA TCAGCTCACT CAAAGGCGGT AATACGGTTA TCCACAGAAT CA - #GGGGATAA     4765     - CGCAGGAAAG AACATGTGAG CAAAAGGCCA GCAAAAGGCC AGGAACCGTA AA - #AAGGCCGC     4825     - GTTGCTGGCG TTTTTCCATA GGCTCCGCCC CCCTGACGAG CATCACAAAA AT - #CGACGCTC     4885     - AAGTCAGAGG TGGCGAAACC CGACAGGACT ATAAAGATAC CAGGCGTTTC CC - #CCTGGAAG     4945     - CTCCCTCGTG CGCTCTCCTG TTCCGACCCT GCCGCTTACC GGATACCTGT CC - #GCCTTTCT     5005     - CCCTTCGGGA AGCGTGGCGC TTTCTCAATG CTCACGCTGT AGGTATCTCA GT - #TCGGTGTA     5065     - GGTCGTTCGC TCCAAGCTGG GCTGTGTGCA CGAACCCCCC GTTCAGCCCG AC - #CGCTGCGC     5125     - CTTATCCGGT AACTATCGTC TTGAGTCCAA CCCGGTAAGA CACGACTTAT CG - #CCACTGGC     5185     - AGCAGCCACT GGTAACAGGA TTAGCAGAGC GAGGTATGTA GGCGGTGCTA CA - #GAGTTCTT     5245     - GAAGTGGTGG CCTAACTACG GCTACACTAG AAGGACAGTA TTTGGTATCT GC - #GCTCTGCT     5305     - GAAGCCAGTT ACCTTCGGAA AAAGAGTTGG TAGCTCTTGA TCCGGCAAAC AA - #ACCACCGC     5365     - TGGTAGCGGT GGTTTTTTTG TTTGCAAGCA GCAGATTACG CGCAGAAAAA AA - #GGATCTCA     5425     - AGAAGATCCT TTGATCTTTT CTACGGGGTC TGACGCTCAG TGGAACGAAA AC - #TCACGTTA     5485     - AGGGATTTTG GTCATGAGAT TATCAAAAAG GATCTTCACC TAGATCCTTT TA - #AATTAAAA     5545     - ATGAAGTTTT AAATCAATCT AAAGTATATA TGAGTAAACT TGGTCTGACA GT - #TACCAATG     5605     - CTTAATCAGT GAGGCACCTA TCTCAGCGAT CTGTCTATTT CGTTCATCCA TA - #GTTGCCTG     5665     - ACTCCCCGTC GTGTAGATAA CTACGATACG GGAGGGCTTA CCATCTGGCC CC - #AGTGCTGC     5725     - AATGATACCG CGAGACCCAC GCTCACCGGC TCCAGATTTA TCAGCAATAA AC - #CAGCCAGC     5785     - CGGAAGGGCC GAGCGCAGAA GTGGTCCTGC AACTTTATCC GCCTCCATCC AG - #TCTATTAA     5845     - TTGTTGCCGG GAAGCTAGAG TAAGTAGTTC GCCAGTTAAT AGTTTGCGCA AC - #GTTGTTGC     5905     - CATTGCTACA GGCATCGTGG TGTCACGCTC GTCGTTTGGT ATGGCTTCAT TC - #AGCTCCGG     5965     - TTCCCAACGA TCAAGGCGAG TTACATGATC CCCCATGTTG TGCAAAAAAG CG - #GTTAGCTC     6025     - CTTCGGTCCT CCGATCGTTG TCAGAAGTAA GTTGGCCGCA GTGTTATCAC TC - #ATGGTTAT     6085     - GGCAGCACTG CATAATTCTC TTACTGTCAT GCCATCCGTA AGATGCTTTT CT - #GTGACTGG     6145     - TGAGTACTCA ACCAAGTCAT TCTGAGAATA GTGTATGCGG CGACCGAGTT GC - #TCTTGCCC     6205     - GGCGTCAATA CGGGATAATA CCGCGCCACA TAGCAGAACT TTAAAAGTGC TC - #ATCATTGG     6265     - AAAACGTTCT TCGGGGCGAA AACTCTCAAG GATCTTACCG CTGTTGAGAT CC - #AGTTCGAT     6325     - GTAACCCACT CGTGCACCCA ACTGATCTTC AGCATCTTTT ACTTTCACCA GC - #GTTTCTGG     6385     - GTGAGCAAAA ACAGGAAGGC AAAATGCCGC AAAAAAGGGA ATAAGGGCGA CA - #CGGAAATG     6445     - TTGAATACTC ATACTCTTCC TTTTTCAATA TTATTGAAGC ATTTATCAGG GT - #TATTGTCT     6505     - CATGAGCGGA TACATATTTG AATGTATTTA GAAAAATAAA CAAATAGGGG TT - #CCGCGCAC     6565     - ATTTCCCCGA AAAGTGCCAC CTGACGTCTA AGAAACCATT ATTATCATGA CA - #TTAACCTA     6625     - TAAAAATAGG CGTATCACGA GGCCCTTTCG TCTCGCGCGT TTCGGTGATG AC - #GGTGAAAA     6685     - CCTCTGACAC ATGCAGCTCC CGGAGACGGT CACAGCTTGT CTGTAAGCGG AT - #GCCGGGAG     6745     - CAGACAAGCC CGTCAGGGCG CGTCAGCGGG TGTTGGCGGG TGTCGGGGCT GG - #CTTAACTA     6805     - TGCGGCATCA GAGCAGATTG TACTGAGAGT GCACCATATG CGGTGTGAAA TA - #CCGCACAG     6865     - ATGCGTAAGG AGAAAATACC GCATCAGGCG CCATTCGCCA TTCAGGCTGC GC - #AACTGTTG     6925     - GGAAGGGCGA TCGGTGCGGG CCTCTTCGCT ATTACGCCAG CTGGCGAAAG GG - #GGATGTGC     6985     - TGCAAGGCGA TTAAGTTGGG TAACGCCAGG GTTTTCCCAG TCACGACGTT GT - #AAAACGAC     7045     - GGCCAGTAAG CTTGGCTGCA GGTCGAGATC CACGTGTGGA AGATATGAAT TT - #TTTTGAGA     7105     - AACTAGATAA GATTAATGAA TATCGGTGTT TTGGTTTTTT CTTGTGGCCG TC - #TTTGTTTA     7165     - TATTGAGATT TTTCAAATCA GTGCGCAAGA CGTGACGTAA GTATCTGAGC TA - #GTTTTTAT     7225     - TTTTCTACTA ATTTGGTCGT TTATTTCGGC GTGTAGGACA TGGCAACCGG GC - #CTGAATTT     7285     - CGCGGGTATT CTGTTTCTAT TCCAACTTTT TCTTGATCCG CAGCCATTAA CG - #ACTTTTGA     7345     - ATAGATACGC TGACACGCCA AGCCTCGCTA GTCAAAAGTG TACCAAACAA CG - #CTTTACAG     7405     - CAAGAACGGA ATGCGCGTGA CGCTCGCGGT GACGCCATTT CGCCTTTTCA GA - #AATGGATA     7465     - AATAGCCTTG CTTCCTATTA TATCTTCCCA AATTACCAAT ACATTACACT AG - #CATCTGAA     7525     # 7566             GATA CACCAAATCG GTACCAAAAC C     __________________________________________________________________________ 

We claim:
 1. A process for modifying the coding region of a Bacillus thuringiensis insecticidal crystal protein (Bt ICP) gene to be expressed in a plant cell; which process comprises the following steps:identifying in the coding region of said Bt ICP gene at least one DNA sequence encoding an abortive intron; and modifying said coding region in a translationally neutral manner to obtain a modified coding region in which said at least one DNA sequence encoding an abortive intron has been inactivated, wherein said DNA sequence encoding an abortive intron can be identified by a process comprising the steps of:(i) introducing said coding region under control of a plant-expressible promoter in plant cells, (ii) amplifying DNA fragments obtained from mRNA transcribed from said coding region in said plant cells, (iii) localizing a gap in said DNA fragments with a size smaller than the size expected for a mature mRNA by aligning said DNA fragments with the DNA sequence encoding a full-size unprocessed RNA;wherein said gap is identified as a DNA sequence encoding an abortive intron when inactivation of splice sites surrounding the abortive intron results in an increase of the level of proper sized mRNA upon transcription in plant cells.
 2. The process of claim 1, wherein the coding region of said Bt ICP gene is modified in a translationally neutral manner by introducing at least one of the following modifications in said coding region;a) introducing a DNA encoding an intron, spliced in the plant cell; and b) replacing amino acid codons in the coding region by other codons encoding the same amino acids.
 3. The process of claim 2, wherein said coding region encodes a toxic portion of said ICP.
 4. The process of claim 2, wherein the ATG translation initiation codon of said coding region has been replaced by the following sequence: AAAACCATGGCT.
 5. The process of claim 4, wherein the coding region which is modified is that of the cryItb14 gene.
 6. The process of claim 2, wherein said coding region encodes a Bt2 ICP and wherein the first 28 N-terminal codons of said coding region have been replaced by an ATG codon.
 7. The process of claim 2, wherein said Bt ICP gene is a bt2 gene, a bt884 gene, a cryIAb6 gene, a cryIAb22 gene, a bt14 gene, a bt15 gene, or a bt18 gene.
 8. The process of claim 7, wherein said Bt ICP gene is a bt2, a bt884 or a cryIAb22 gene and wherein a cryptic promoter is inactivated by translationally neutral modifications between nucleotide positions 742 and 813 in the coding region of bt884.
 9. The process of claim 7, wherein said Bt ICP gene is a bt2, bt884, cryIAb22, or cryIAb6 gene and wherein said at least one DNA sequence encoding an abortive intron is inactivated by translationally neutral modifications in a region within 10 nucleotides of one or more of the following sequences in the coding region: AAG:GTGGGG, AGT:GTAAGT, and CGG:GTAAGA.
 10. The process of claim 1, wherein said coding region after modification differs from a native coding region of a Bt ICP gene by having less than 3% of the nucleotides in said native coding region changed from A or T to G or C nucleotides.
 11. The process of claim 1, wherein said coding region after modification differs from a native coding region of a Bt ICP gene by having less than 1% of the nucleotides in said native coding region changed from A or T to G or C nucleotides.
 12. The process of claim 1, wherein the abortive intron is inactivated by translationally neutral modification in said coding region in about 3 to about 10 nucleotides on either side of the 5' and 3' abortive intron splice sites.
 13. The process of claim 1, which further comprises the steps of:identifying in the coding region of said Bt ICP gene, at least one cryptic promoter in either a sense or an anti-sense orientation; and modifying said coding region in a translationally neutral manner to obtain a modified coding region in which said at least one cryptic promoter has been inactivated,wherein said cryptic promoter can be identified by a process comprising the steps of: (i) identifying a pausing region in said coding sequence inhibiting elongation of transcription by RNA polymerase II by means of run-on analysis on plant cell nuclei containing said coding sequence in their nuclear genome; (ii) cloning said pausing region or a part thereof in two orientations in a transcription initiation-probe vector downstream of an enhancer of a plant promoter and upstream of a DNA sequence that can be transcribed; (iii) introducing said vector into plant cells; (iv) detecting the accumulation of RNA species which is initiated from the pausing region; and (v) localizing the transcription initiation site in said RNA species;wherein said pausing region is identified as a cryptic promoter when said RNA is produced from a transcription initiation site located in said pausing region or the part thereof.
 14. The process of claim 13, wherein said cryptic promoter comprises a CCAAT sequence or a TATA sequence.
 15. The process of claim 13, wherein the abortive intron is inactivated by translationally neutral modification in said coding region in about 3 to about 10 nucleotides on either side of the 5' and 3' abortive intron splice sites, and wherein the cryptic promoter is inactivated by translationally neutral modification in said coding region of 20 to 90 nucleotides upstream of the experimentally determined transcription initiation site of said cryptic promoter.
 16. A method of improving the production level of a Bt ICP protein in a plant cell, wherein said method comprises:identifying, in a coding region of a nucleic acid encoding said Bt ICP protein, at least one DNA sequence encoding a plant abortive intron; modifying said coding region in a translationally neutral manner to obtain a modified coding region in which said at least one DNA sequence encoding a plant abortive intron is inactivated; and introducing said modified coding region into said plant cell under the control of a promoter functional in a plant cell.
 17. A process for protecting a plant from an insect pest, comprising the steps of:transforming the genome of the plant with a chimeric gene which comprises the following operably-linked DNA fragments:(1) a promoter for directing transcription in plant cells; (2) a modified coding region obtained by the process of claim 1; (3) a transcript 3' end formation and polyadenylation region functional in plant cells.
 18. The process of claim 17, wherein said promoter is a 35S promoter, a TR1' promoter, or a TR2' promoter.
 19. The process of claim 17, wherein said transcript 3' end formation and polyadenylation region is from the chalcone synthase gene.
 20. A modified Bt ICP region, obtained from a native Bt ICP coding region by the process of claim 1 wherein said coding region of said Bt ICP gene is modified by making translationally neutral replacements in the DNA sequence encoding a splice site of said abortive intron.
 21. A modified Bt ICP coding region of claim 20, wherein said modified Bt ICP coding region encodes a protein which is truncated at its N-and/or C-terminal end.
 22. A modified Bt ICP coding region obtained from a native Bt ICP coding region by the process of claim 13 wherein the coding region of said Bt ICP gene is modified by making translationally neutral nucleotide replacements in said cryptic promoter and making translationally neutral nucleotide replacements in the DNA sequence encoding a splice site of said abortive intron.
 23. A modified Bt ICP coding region obtained from a native Bt ICP coding region by the process of claim 1, wherein said at least one DNA sequence encoding an abortive intron is inactivated by making translationally neutral nucleotide replacements in said native Bt ICP coding region in about 3 to about 10 nucleotides on either side of a 5' and a 3' abortive intron splice site.
 24. A modified Bt ICP coding region obtained from a native Bt ICP coding region by the process of claim 13, wherein said at least one cryptic promoter is inactivated by making translationally neutral modifications in said native Bt ICP coding region of 20 to 90 nucleotides upstream of the experimentally determined transcription initiation site of said cryptic promoter and said abortive intron is inactivated by making translationally neutral nucleotide replacements in a DNA sequence encoding a splice site of said abortive intron.
 25. A modified Bt ICP coding region, obtained from a native Bt ICP coding region by making translationally neutral nucleotide replacements in the abortive intron 5' splice site motifs AGT:GTAAGT, CGG:GTAAGA and AAG:GTGGGG.
 26. A plant cell, transformed to comprise the modified Bt ICP coding region of claim
 20. 27. A plant, modified to comprise the modified Bt ICP coding region of claim
 20. 